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/i18n/locales/en.json

@@ -183,6 +183,10 @@
         "title": "Cost Pricing",
         "description": "Manage token pricing rules for each model"
       },
+      "globalProxy": {
+        "title": "Global Outbound Proxy",
+        "description": "Configure proxy for CC Switch to access external APIs"
+      },
       "data": {
         "title": "Data Management",
         "description": "Import/export configurations and backup/restore"
@@ -271,7 +275,21 @@
     "restartLater": "Restart Later",
     "restartFailed": "Application restart failed, please manually close and reopen.",
     "devModeRestartHint": "Dev Mode: Automatic restart not supported, please manually restart the application.",
-    "saving": "Saving..."
+    "saving": "Saving...",
+    "globalProxy": {
+      "label": "Global Proxy",
+      "hint": "Proxy all requests (API, Skills download, etc.). Leave empty for direct connection.",
+      "username": "Username (optional)",
+      "password": "Password (optional)",
+      "test": "Test Connection",
+      "scan": "Scan Local Proxies",
+      "clear": "Clear",
+      "scanFailed": "Scan failed: {{error}}",
+      "saved": "Proxy settings saved",
+      "saveFailed": "Save failed: {{error}}",
+      "testSuccess": "Connected! Latency {{latency}}ms",
+      "testFailed": "Connection failed: {{error}}"
+    }
   },
   "apps": {
     "claude": "Claude Code",

src/i18n/locales/ja.json

@@ -183,6 +183,10 @@
         "title": "コスト計算",
         "description": "各モデルのトークン料金ルールを管理"
       },
+      "globalProxy": {
+        "title": "グローバル送信プロキシ",
+        "description": "CC Switch が外部 API にアクセスする際のプロキシを設定"
+      },
       "data": {
         "title": "データ管理",
         "description": "設定のインポート/エクスポートとバックアップ/復元"
@@ -271,7 +275,21 @@
     "restartLater": "後で再起動",
     "restartFailed": "アプリの再起動に失敗しました。手動で閉じて再度開いてください。",
     "devModeRestartHint": "開発モードでは自動再起動をサポートしていません。手動で再起動してください。",
-    "saving": "保存中..."
+    "saving": "保存中...",
+    "globalProxy": {
+      "label": "グローバルプロキシ",
+      "hint": "すべてのリクエスト（API、Skills ダウンロードなど）をプロキシ経由で送信します。空欄で直接接続。",
+      "username": "ユーザー名（任意）",
+      "password": "パスワード（任意）",
+      "test": "接続テスト",
+      "scan": "ローカルプロキシをスキャン",
+      "clear": "クリア",
+      "scanFailed": "スキャンに失敗しました: {{error}}",
+      "saved": "プロキシ設定を保存しました",
+      "saveFailed": "保存に失敗しました: {{error}}",
+      "testSuccess": "接続成功！遅延 {{latency}}ms",
+      "testFailed": "接続に失敗しました: {{error}}"
+    }
   },
   "apps": {
     "claude": "Claude Code",

src/i18n/locales/zh.json

@@ -183,6 +183,10 @@
         "title": "成本定价",
         "description": "管理各模型 Token 计费规则"
       },
+      "globalProxy": {
+        "title": "全局出站代理",
+        "description": "配置 CC Switch 访问外部 API 时使用的代理"
+      },
       "data": {
         "title": "数据管理",
         "description": "导入导出配置与备份恢复"
@@ -271,7 +275,21 @@
     "restartLater": "稍后重启",
     "restartFailed": "应用重启失败，请手动关闭后重新打开。",
     "devModeRestartHint": "开发模式下不支持自动重启，请手动重新启动应用。",
-    "saving": "正在保存..."
+    "saving": "正在保存...",
+    "globalProxy": {
+      "label": "全局代理",
+      "hint": "代理所有请求（API、Skills 下载等）。留空表示直连。",
+      "username": "用户名（可选）",
+      "password": "密码（可选）",
+      "test": "测试连接",
+      "scan": "扫描本地代理",
+      "clear": "清除",
+      "scanFailed": "扫描失败：{{error}}",
+      "saved": "代理设置已保存",
+      "saveFailed": "保存失败：{{error}}",
+      "testSuccess": "连接成功！延迟 {{latency}}ms",
+      "testFailed": "连接失败：{{error}}"
+    }
   },
   "apps": {
     "claude": "Claude Code",