fix(proxy): resolve 404 error and auto-setup proxy targets

Issues fixed:
1. Route prefix mismatch - Live config was set to use /claude, /codex,
   /gemini prefixes but server only had routes without prefixes
2. Proxy targets not auto-configured - start_with_takeover only modified
   Live config but didn't set is_proxy_target=true for current providers

Changes:
- Add prefixed routes (/claude/v1/messages, /codex/v1/*, /gemini/v1beta/*)
  to server.rs for backward compatibility
- Remove URL prefixes from takeover_live_configs() - server can route
  by API endpoint path alone (/v1/messages=Claude, /v1/chat/completions=Codex)
- Add setup_proxy_targets() method that automatically sets current providers
  as proxy targets when starting proxy with takeover
- Unify proxy toggle in SettingsPage to use takeover mode (same as main UI)
- Fix error message extraction in useProxyStatus hooks
- Fix provider switch logic to check both takeover flag AND proxy running state

src-tauri/src/proxy/server.rs

@@ -148,17 +148,24 @@ impl ProxyServer {
             // 健康检查
             .route("/health", get(handlers::health_check))
             .route("/status", get(handlers::get_status))
-            // Claude API
+            // Claude API (支持带前缀和不带前缀两种格式)
             .route("/v1/messages", post(handlers::handle_messages))
-            // OpenAI Chat Completions API (Codex CLI)
+            .route("/claude/v1/messages", post(handlers::handle_messages))
+            // OpenAI Chat Completions API (Codex CLI，支持带前缀和不带前缀)
             .route(
                 "/v1/chat/completions",
                 post(handlers::handle_chat_completions),
             )
-            // OpenAI Responses API (Codex CLI)
+            .route(
+                "/codex/v1/chat/completions",
+                post(handlers::handle_chat_completions),
+            )
+            // OpenAI Responses API (Codex CLI，支持带前缀和不带前缀)
             .route("/v1/responses", post(handlers::handle_responses))
-            // Gemini API
+            .route("/codex/v1/responses", post(handlers::handle_responses))
+            // Gemini API (支持带前缀和不带前缀)
             .route("/v1beta/*path", post(handlers::handle_gemini))
+            .route("/gemini/v1beta/*path", post(handlers::handle_gemini))
             .layer(cors)
             .with_state(self.state.clone())
     }

src-tauri/src/proxy/types.rs

@@ -15,6 +15,9 @@ pub struct ProxyConfig {
     pub request_timeout: u64,
     /// 是否启用日志
     pub enable_logging: bool,
+    /// 是否正在接管 Live 配置
+    #[serde(default)]
+    pub live_takeover_active: bool,
 }
 
 impl Default for ProxyConfig {
@@ -26,6 +29,7 @@ impl Default for ProxyConfig {
             max_retries: 3,
             request_timeout: 300,
             enable_logging: true,
+            live_takeover_active: false,
         }
     }
 }
@@ -117,3 +121,14 @@ pub struct ProxyUsageRecord {
     pub error: Option<String>,
     pub timestamp: String,
 }
+
+/// Live 配置备份记录
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct LiveBackup {
+    /// 应用类型 (claude/codex/gemini)
+    pub app_type: String,
+    /// 原始配置 JSON
+    pub original_config: String,
+    /// 备份时间
+    pub backed_up_at: String,
+}