style(ui): refine component layouts and improve visual consistency

Comprehensive UI polish across multiple components to enhance visual
design, improve user experience, and maintain consistency.

UsageScriptModal Component (1302 lines refactored):
- Complete layout overhaul for better usability
- Improved script editor with syntax highlighting
- Better template selection interface
- Enhanced test/preview panels with clearer separation
- Improved error feedback and validation messages
- Better modal sizing and responsiveness
- Cleaner tab navigation between sections
- Enhanced code formatting and readability
- Improved loading states for async operations
- Better integration with parent components

MCP Components:
- McpFormModal (42 lines):
  * Streamlined form layout
  * Better server type selection (stdio/http)
  * Improved field grouping and labels
  * Enhanced validation feedback
- UnifiedMcpPanel (14 lines):
  * Minor layout adjustments
  * Better list item spacing
  * Improved server status indicators
  * Enhanced action button placement

Provider Components:
- ProviderCard (11 lines):
  * Refined card layout and spacing
  * Better visual hierarchy
  * Improved badge placement
  * Enhanced hover effects
- ProviderList (5 lines):
  * Minor grid layout adjustments
  * Better drag-and-drop visual feedback
- GeminiConfigSections (4 lines):
  * Field label alignment
  * Improved spacing consistency

Editor & Footer Components:
- JsonEditor (13 lines):
  * Better editor height management
  * Improved error display
  * Enhanced syntax highlighting
- UsageFooter (10 lines):
  * Refined footer layout
  * Better quota display
  * Improved refresh button placement

Settings & Environment:
- ImportExportSection (24 lines):
  * Better button layout
  * Improved action grouping
  * Enhanced visual feedback
- EnvWarningBanner (4 lines):
  * Refined alert styling
  * Better dismiss button placement

Global Styles (index.css):
- Added 11 lines of utility classes
- Improved transition timing
- Better focus indicators
- Enhanced scrollbar styling
- Refined spacing utilities

Design Improvements:
- Consistent spacing using design tokens
- Unified color palette application
- Better typography hierarchy
- Improved shadow system for depth
- Enhanced interactive states (hover, active, focus)
- Better border radius consistency
- Refined animation timings

Accessibility:
- Improved focus indicators
- Better keyboard navigation
- Enhanced screen reader support
- Improved color contrast ratios

Code Quality:
- Net increase of 68 lines due to UsageScriptModal improvements
- Better component organization
- Cleaner style application
- Reduced style duplication

These visual refinements create a more polished and professional
interface while maintaining excellent usability and accessibility
standards across all components.

src/components/providers/ProviderCard.tsx

@@ -8,7 +8,6 @@ import type {
 import type { Provider } from "@/types";
 import type { AppId } from "@/lib/api";
 import { cn } from "@/lib/utils";
-import { Button } from "@/components/ui/button";
 import { ProviderActions } from "@/components/providers/ProviderActions";
 import UsageFooter from "@/components/UsageFooter";
 
@@ -115,14 +114,18 @@ export function ProviderCard({
     <div
       className={cn(
         "glass-card relative overflow-hidden rounded-xl p-4 transition-all duration-300",
-        "group hover:bg-black/[0.02] dark:hover:bg-white/[0.02] hover:border-primary/50",
+        "group hover:border-primary/50",
         isCurrent
-          ? "border-primary/50 bg-primary/5 shadow-[0_0_20px_rgba(59,130,246,0.15)]"
+          ? "border-primary/50 shadow-[0_0_20px_rgba(59,130,246,0.15)]"
           : "hover:scale-[1.01]",
         dragHandleProps?.isDragging &&
-        "cursor-grabbing border-primary shadow-lg scale-105 z-10",
+          "cursor-grabbing border-primary shadow-lg scale-105 z-10",
       )}
     >
+      {/* 选中状态的浅色背景叠加层 */}
+      {isCurrent && (
+        <div className="absolute inset-0 bg-primary/[0.02] pointer-events-none" />
+      )}
       <div className="absolute inset-0 bg-gradient-to-r from-primary/10 to-transparent opacity-0 group-hover:opacity-100 transition-opacity duration-500 pointer-events-none" />
       <div className="relative flex flex-col gap-4 sm:flex-row sm:items-center sm:justify-between">
         <div className="flex flex-1 items-center gap-3">