Refactor/simplify proxy logs (#585)

* 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

* 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

src/config/claudeProviderPresets.ts

@@ -405,9 +405,7 @@ export const providerPresets: ProviderPreset[] = [
       },
     },
     // 请求地址候选（用于地址管理/测速）
-    endpointCandidates: [
-      "https://api.aigocode.com",
-    ],
+    endpointCandidates: ["https://api.aigocode.com"],
     category: "third_party",
     isPartner: true, // 合作伙伴
     partnerPromotionKey: "aigocode", // 促销信息 i18n key

src/config/codexProviderPresets.ts

@@ -181,7 +181,11 @@ requires_openai_auth = true`,
     apiKeyUrl: "https://aigocode.com/invite/CC-SWITCH",
     category: "third_party",
     auth: generateThirdPartyAuth(""),
-    config: generateThirdPartyConfig("aigocode", "https://api.aigocode.com/openai", "gpt-5.2"),
+    config: generateThirdPartyConfig(
+      "aigocode",
+      "https://api.aigocode.com/openai",
+      "gpt-5.2",
+    ),
     endpointCandidates: ["https://api.aigocode.com"],
     isPartner: true, // 合作伙伴
     partnerPromotionKey: "aigocode", // 促销信息 i18n key

src/config/geminiProviderPresets.ts

@@ -70,7 +70,7 @@ export const geminiProviderPresets: GeminiProviderPreset[] = [
       "https://www.packyapi.com",
     ],
     icon: "packycode",
-  },  
+  },
   {
     name: "Cubence",
     websiteUrl: "https://cubence.com",