Feat/auto failover (#367)

* feat(db): add circuit breaker config table and provider proxy target APIs

Add database support for auto-failover feature:

- Add circuit_breaker_config table for storing failover thresholds
- Add get/update_circuit_breaker_config methods in proxy DAO
- Add reset_provider_health method for manual recovery
- Add set_proxy_target and get_proxy_targets methods in providers DAO
  for managing multi-provider failover configuration

* feat(proxy): implement circuit breaker and provider router for auto-failover

Add core failover logic:

- CircuitBreaker: Tracks provider health with three states:
  - Closed: Normal operation, requests pass through
  - Open: Circuit broken after consecutive failures, skip provider
  - HalfOpen: Testing recovery with limited requests
- ProviderRouter: Routes requests across multiple providers with:
  - Health tracking and automatic failover
  - Configurable failure/success thresholds
  - Auto-disable proxy target after reaching failure threshold
  - Support for manual circuit breaker reset
- Export new types in proxy module

* feat(proxy): add failover Tauri commands and integrate with forwarder

Expose failover functionality to frontend:

- Add Tauri commands: get_proxy_targets, set_proxy_target,
  get_provider_health, reset_circuit_breaker,
  get/update_circuit_breaker_config, get_circuit_breaker_stats
- Register all new commands in lib.rs invoke handler
- Update forwarder with improved error handling and logging
- Integrate ProviderRouter with proxy server startup
- Add provider health tracking in request handlers

* feat(frontend): add failover API layer and TanStack Query hooks

Add frontend data layer for failover management:

- Add failover.ts API: Tauri invoke wrappers for all failover commands
- Add failover.ts query hooks: TanStack Query mutations and queries
  - useProxyTargets, useProviderHealth queries
  - useSetProxyTarget, useResetCircuitBreaker mutations
  - useCircuitBreakerConfig query and mutation
- Update queries.ts with provider health query key
- Update mutations.ts to invalidate health on provider changes
- Add CircuitBreakerConfig and ProviderHealth types

* feat(ui): add auto-failover configuration UI and provider health display

Add comprehensive UI for failover management:

Components:
- ProviderHealthBadge: Display provider health status with color coding
- CircuitBreakerConfigPanel: Configure failure/success thresholds,
  timeout duration, and error rate limits
- AutoFailoverConfigPanel: Manage proxy targets with drag-and-drop
  priority ordering and individual enable/disable controls
- ProxyPanel: Integrate failover tabs for unified proxy management

Provider enhancements:
- ProviderCard: Show health badge and proxy target indicator
- ProviderActions: Add "Set as Proxy Target" action
- EditProviderDialog: Add is_proxy_target toggle
- ProviderList: Support proxy target filtering mode

Other:
- Update App.tsx routing for settings integration
- Update useProviderActions hook with proxy target mutation
- Fix ProviderList tests for updated component API

* fix(usage): stabilize date range to prevent infinite re-renders

* feat(backend): add tool version check command

Add get_tool_versions command to check local and latest versions of
Claude, Codex, and Gemini CLI tools:

- Detect local installed versions via command line execution
- Fetch latest versions from npm registry (Claude, Gemini)
  and GitHub releases API (Codex)
- Return comprehensive version info including error details
  for uninstalled tools
- Register command in Tauri invoke handler

* style(ui): format accordion component code style

Apply consistent code formatting to accordion component:
- Convert double quotes to semicolons at line endings
- Adjust indentation to 2-space standard
- Align with project code style conventions

* refactor(providers): update provider card styling to use theme tokens

Replace hardcoded color classes with semantic design tokens:
- Use bg-card, border-border, text-card-foreground instead of glass-card
- Replace gray/white color literals with muted/foreground tokens
- Change proxy target indicator color from purple to green
- Improve hover states with border-border-active
- Ensure consistent dark mode support via CSS variables

* refactor(proxy): simplify auto-failover config panel structure

Restructure AutoFailoverConfigPanel for better integration:
- Remove internal Card wrapper and expansion toggle (now handled by parent)
- Extract enabled state to props for external control
- Simplify loading state display
- Clean up redundant CardHeader/CardContent wrappers
- ProxyPanel: reduce complexity by delegating to parent components

* feat(settings): enhance settings page with accordion layout and tool versions

Major settings page improvements:

AboutSection:
- Add local tool version detection (Claude, Codex, Gemini)
- Display installed vs latest version comparison with visual indicators
- Show update availability badges and environment check cards

SettingsPage:
- Reorganize advanced settings into collapsible accordion sections
- Add proxy control panel with inline status toggle
- Integrate auto-failover configuration with accordion UI
- Add database and cost calculation config sections

DirectorySettings & WindowSettings:
- Minor styling adjustments for consistency

settings.ts API:
- Add getToolVersions() wrapper for new backend command

* refactor(usage): restructure usage dashboard components

Comprehensive usage statistics panel refactoring:

UsageDashboard:
- Reorganize layout with improved section headers
- Add better loading states and empty state handling

ModelStatsTable & ProviderStatsTable:
- Minor styling updates for consistency

ModelTestConfigPanel & PricingConfigPanel:
- Simplify component structure
- Remove redundant Card wrappers
- Improve form field organization

RequestLogTable:
- Enhance table layout with better column sizing
- Improve pagination controls

UsageSummaryCards:
- Update card styling with semantic tokens
- Better responsive grid layout

UsageTrendChart:
- Refine chart container styling
- Improve legend and tooltip display

* chore(deps): add accordion and animation dependencies

Package updates:
- Add @radix-ui/react-accordion for collapsible sections
- Add cmdk for command palette support
- Add framer-motion for enhanced animations

Tailwind config:
- Add accordion-up/accordion-down animations
- Update darkMode config to support both selector and class
- Reorganize color and keyframe definitions for clarity

* style(app): update header and app switcher styling

App.tsx:
- Replace glass-header with explicit bg-background/80 backdrop-blur
- Update navigation button container to use bg-muted

AppSwitcher:
- Replace hardcoded gray colors with semantic muted/foreground tokens
- Ensure consistent dark mode support via CSS variables
- Add group class for better hover state transitions

src/components/settings/WindowSettings.tsx

@@ -1,6 +1,7 @@
 import { Switch } from "@/components/ui/switch";
 import { useTranslation } from "react-i18next";
 import type { SettingsFormState } from "@/hooks/useSettings";
+import { AppWindow, MonitorUp, Power } from "lucide-react";
 
 interface WindowSettingsProps {
   settings: SettingsFormState;
@@ -12,40 +13,46 @@ export function WindowSettings({ settings, onChange }: WindowSettingsProps) {
 
   return (
     <section className="space-y-4">
-      <header className="space-y-1">
+      <div className="flex items-center gap-2 pb-2 border-b border-border/40">
+        <AppWindow className="h-4 w-4 text-primary" />
         <h3 className="text-sm font-medium">{t("settings.windowBehavior")}</h3>
-        <p className="text-xs text-muted-foreground">
-          {t("settings.windowBehaviorHint")}
-        </p>
-      </header>
+      </div>
 
-      <ToggleRow
-        title={t("settings.launchOnStartup")}
-        description={t("settings.launchOnStartupDescription")}
-        checked={!!settings.launchOnStartup}
-        onCheckedChange={(value) => onChange({ launchOnStartup: value })}
-      />
+      <div className="space-y-3">
+        <ToggleRow
+          icon={<Power className="h-4 w-4 text-orange-500" />}
+          title={t("settings.launchOnStartup")}
+          description={t("settings.launchOnStartupDescription")}
+          checked={!!settings.launchOnStartup}
+          onCheckedChange={(value) => onChange({ launchOnStartup: value })}
+        />
 
-      <ToggleRow
-        title={t("settings.minimizeToTray")}
-        description={t("settings.minimizeToTrayDescription")}
-        checked={settings.minimizeToTrayOnClose}
-        onCheckedChange={(value) => onChange({ minimizeToTrayOnClose: value })}
-      />
+        <ToggleRow
+          icon={<AppWindow className="h-4 w-4 text-blue-500" />}
+          title={t("settings.minimizeToTray")}
+          description={t("settings.minimizeToTrayDescription")}
+          checked={settings.minimizeToTrayOnClose}
+          onCheckedChange={(value) =>
+            onChange({ minimizeToTrayOnClose: value })
+          }
+        />
 
-      <ToggleRow
-        title={t("settings.enableClaudePluginIntegration")}
-        description={t("settings.enableClaudePluginIntegrationDescription")}
-        checked={!!settings.enableClaudePluginIntegration}
-        onCheckedChange={(value) =>
-          onChange({ enableClaudePluginIntegration: value })
-        }
-      />
+        <ToggleRow
+          icon={<MonitorUp className="h-4 w-4 text-purple-500" />}
+          title={t("settings.enableClaudePluginIntegration")}
+          description={t("settings.enableClaudePluginIntegrationDescription")}
+          checked={!!settings.enableClaudePluginIntegration}
+          onCheckedChange={(value) =>
+            onChange({ enableClaudePluginIntegration: value })
+          }
+        />
+      </div>
     </section>
   );
 }
 
 interface ToggleRowProps {
+  icon: React.ReactNode;
   title: string;
   description?: string;
   checked: boolean;
@@ -53,18 +60,24 @@ interface ToggleRowProps {
 }
 
 function ToggleRow({
+  icon,
   title,
   description,
   checked,
   onCheckedChange,
 }: ToggleRowProps) {
   return (
-    <div className="flex items-start justify-between gap-4 rounded-lg border border-border-default p-4">
-      <div className="space-y-1">
-        <p className="text-sm font-medium leading-none">{title}</p>
-        {description ? (
-          <p className="text-xs text-muted-foreground">{description}</p>
-        ) : null}
+    <div className="flex items-center justify-between gap-4 rounded-xl border border-border bg-card/50 p-4 transition-colors hover:bg-muted/50">
+      <div className="flex items-center gap-3">
+        <div className="flex h-8 w-8 items-center justify-center rounded-lg bg-background ring-1 ring-border">
+          {icon}
+        </div>
+        <div className="space-y-1">
+          <p className="text-sm font-medium leading-none">{title}</p>
+          {description ? (
+            <p className="text-xs text-muted-foreground">{description}</p>
+          ) : null}
+        </div>
       </div>
       <Switch
         checked={checked}