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-tauri/src/database/dao/settings.rs

@@ -63,6 +63,41 @@ impl Database {
         }
     }
 
+    // --- 全局出站代理 ---
+
+    /// 全局代理 URL 的存储键名
+    const GLOBAL_PROXY_URL_KEY: &'static str = "global_proxy_url";
+
+    /// 获取全局出站代理 URL
+    ///
+    /// 返回 None 表示未配置或已清除代理（直连）
+    /// 返回 Some(url) 表示已配置代理
+    pub fn get_global_proxy_url(&self) -> Result<Option<String>, AppError> {
+        self.get_setting(Self::GLOBAL_PROXY_URL_KEY)
+    }
+
+    /// 设置全局出站代理 URL
+    ///
+    /// - 传入非空字符串：启用代理
+    /// - 传入空字符串或 None：清除代理设置（直连）
+    pub fn set_global_proxy_url(&self, url: Option<&str>) -> Result<(), AppError> {
+        match url {
+            Some(u) if !u.trim().is_empty() => {
+                self.set_setting(Self::GLOBAL_PROXY_URL_KEY, u.trim())
+            }
+            _ => {
+                // 清除代理设置
+                let conn = lock_conn!(self.conn);
+                conn.execute(
+                    "DELETE FROM settings WHERE key = ?1",
+                    params![Self::GLOBAL_PROXY_URL_KEY],
+                )
+                .map_err(|e| AppError::Database(e.to_string()))?;
+                Ok(())
+            }
+        }
+    }
+
     // --- 代理接管状态管理（已废弃，使用 proxy_config.enabled 替代）---
 
     /// 获取指定应用的代理接管状态