Feature/global proxy (#596)

* refactor(proxy): simplify logging for better readability

- Delete 17 verbose debug logs from handlers, streaming, and response_processor
- Convert excessive INFO logs to DEBUG level for internal processing details
- Add 2 critical INFO logs in forwarder.rs for failover scenarios:
  - Log when switching to next provider after failure
  - Log when all providers have been exhausted
- Fix clippy uninlined_format_args warning

This reduces log noise while maintaining visibility into key user-facing decisions.

* fix: replace unsafe unwrap() calls with proper error handling

- database/dao/mcp.rs: Use map_err for serde_json serialization
- database/dao/providers.rs: Use map_err for settings_config and meta serialization
- commands/misc.rs: Use expect() for compile-time regex pattern
- services/prompt.rs: Use unwrap_or_default() for SystemTime
- deeplink/provider.rs: Replace unwrap() with is_none_or pattern for Option checks

Reduces potential panic points from 26 to 1 (static regex init, safe).

* refactor(proxy): simplify verbose logging output

- Remove response JSON full output logging in response_processor
- Remove per-request INFO logs in provider_router (failover status, provider selection)
- Change model mapping log from INFO to DEBUG
- Change usage logging failure from INFO to WARN
- Remove redundant debug logs for circuit breaker operations

Reduces log noise significantly while preserving important warnings and errors.

* feat(proxy): add structured log codes for i18n support

Add error code system to proxy module logs for multi-language support:

- CB-001~006: Circuit breaker state transitions and triggers
- SRV-001~004: Proxy server lifecycle events
- FWD-001~002: Request forwarding and failover
- FO-001~005: Failover switch operations
- USG-001~002: Usage logging errors

Log format: [CODE] Chinese message
Frontend/log tools can map codes to any language.

New file: src/proxy/log_codes.rs - centralized code definitions

* chore: bump version to 3.9.1

* style: format code with prettier and rustfmt

* fix(ui): allow number inputs to be fully cleared before saving

- Convert numeric state to string type for controlled inputs
- Use isNaN() check instead of || fallback to allow 0 values
- Apply fix to ProxyPanel, CircuitBreakerConfigPanel,
  AutoFailoverConfigPanel, and ModelTestConfigPanel

* feat(pricing): support @ separator in model name matching

- Refactor model name cleaning into chained method calls
- Add @ to - replacement (e.g., gpt-5.2-codex@low → gpt-5.2-codex-low)
- Add test case for @ separator matching

* feat(proxy): add global proxy settings support

Add ability to configure a global HTTP/HTTPS proxy for all outbound
requests including provider API calls, speed tests, and stream checks.

* fix(proxy): improve validation and error handling in proxy config panels

- Add StopTimeout/StopFailed error types for proper stop() error reporting
- Replace silent clamp with validation-and-block in config panels
- Add listenAddress format validation in ProxyPanel
- Use log_codes constants instead of hardcoded strings
- Use once_cell::Lazy for regex precompilation

* fix(proxy): harden error handling and input validation

- Handle RwLock poisoning in settings.rs with unwrap_or_else
- Add fallback for dirs::home_dir() in config modules
- Normalize localhost to 127.0.0.1 in ProxyPanel
- Format IPv6 addresses with brackets for valid URLs
- Strict port validation with pure digit regex
- Treat NaN as validation failure in config panels
- Log warning on cost_multiplier parse failure
- Align timeoutSeconds range to [0, 300] across all panels

* feat(proxy): add local proxy auto-scan and fix hot-reload

- Add scan_local_proxies command to detect common proxy ports
- Fix SkillService not using updated proxy after hot-reload
- Move global proxy settings to advanced tab
- Add error handling for scan failures

* fix(proxy): allow localhost input in proxy address field

* fix(proxy): restore request timeout and fix proxy hot-reload issues

- Add URL scheme validation in build_client (http/https/socks5/socks5h)
- Restore per-request timeout for speedtest, stream_check, usage_script, forwarder
- Fix set_global_proxy_url to validate before persisting to DB
- Mask proxy credentials in all log outputs
- Fix forwarder hot-reload by fetching client on each request

* style: format code with prettier

* fix(proxy): improve global proxy stability and error handling

- Fix RwLock silent failures with explicit error propagation
- Handle init() duplicate calls gracefully with warning log
- Align fallback client config with build_client settings
- Make scan_local_proxies async to avoid UI blocking
- Add mixed mode support for Clash 7890 port (http+socks5)
- Use multiple test targets for better proxy connectivity test
- Clear invalid proxy config on init failure
- Restore timeout constraints in usage_script
- Fix mask_url output for URLs without port
- Add structured error codes [GP-001 to GP-009]

* feat(proxy): add username/password authentication support

- Add separate username and password input fields
- Implement password visibility toggle with eye icon
- Add clear button to reset all proxy fields
- Auto-extract auth info from saved URL and merge on save
- Update i18n translations (zh/en/ja)

* fix(proxy): fix double encoding issue in proxy auth and add debug logs

- Remove encodeURIComponent in mergeAuth() since URL object's
  username/password setters already do percent-encoding automatically
- Add GP-010 debug log for database read operations
- Add GP-011 debug log to track incoming URL info (length, has_auth)
- Fix username.trim() in fallback branch for consistent behavior

src/lib/api/globalProxy.ts

@@ -0,0 +1,85 @@
+/**
+ * 全局出站代理 API
+ *
+ * 提供获取、设置和测试全局代理的功能。
+ */
+
+import { invoke } from "@tauri-apps/api/core";
+
+/**
+ * 代理测试结果
+ */
+export interface ProxyTestResult {
+  success: boolean;
+  latencyMs: number;
+  error: string | null;
+}
+
+/**
+ * 出站代理状态
+ */
+export interface UpstreamProxyStatus {
+  enabled: boolean;
+  proxyUrl: string | null;
+}
+
+/**
+ * 检测到的代理
+ */
+export interface DetectedProxy {
+  url: string;
+  proxyType: string;
+  port: number;
+}
+
+/**
+ * 获取全局代理 URL
+ *
+ * @returns 代理 URL，null 表示未配置（直连）
+ */
+export async function getGlobalProxyUrl(): Promise<string | null> {
+  return invoke<string | null>("get_global_proxy_url");
+}
+
+/**
+ * 设置全局代理 URL
+ *
+ * @param url - 代理 URL（如 http://127.0.0.1:7890 或 socks5://127.0.0.1:1080）
+ *              空字符串表示清除代理（直连）
+ */
+export async function setGlobalProxyUrl(url: string): Promise<void> {
+  try {
+    return await invoke("set_global_proxy_url", { url });
+  } catch (error) {
+    // Tauri invoke 错误可能是字符串
+    throw new Error(typeof error === "string" ? error : String(error));
+  }
+}
+
+/**
+ * 测试代理连接
+ *
+ * @param url - 要测试的代理 URL
+ * @returns 测试结果，包含是否成功、延迟和错误信息
+ */
+export async function testProxyUrl(url: string): Promise<ProxyTestResult> {
+  return invoke<ProxyTestResult>("test_proxy_url", { url });
+}
+
+/**
+ * 获取当前出站代理状态
+ *
+ * @returns 代理状态，包含是否启用和代理 URL
+ */
+export async function getUpstreamProxyStatus(): Promise<UpstreamProxyStatus> {
+  return invoke<UpstreamProxyStatus>("get_upstream_proxy_status");
+}
+
+/**
+ * 扫描本地代理
+ *
+ * @returns 检测到的代理列表
+ */
+export async function scanLocalProxies(): Promise<DetectedProxy[]> {
+  return invoke<DetectedProxy[]>("scan_local_proxies");
+}