feat(proxy): wire Gemini Native format into proxy core and Claude adapter

Integrate gemini_native api_format throughout the proxy pipeline:
- ClaudeAdapter: detect Gemini provider type, Google/GoogleOAuth auth
  strategies, and suppress Anthropic-specific headers for Gemini targets
- Forwarder: Gemini URL resolution, shadow store threading, endpoint
  rewriting to models/*:generateContent with stream/non-stream variants
- Handlers: route Gemini streaming through streaming_gemini adapter and
  non-streaming through transform_gemini converter
- Server/State: add GeminiShadowStore to shared ProxyState
- StreamCheck: support gemini_native health check with proper auth headers

src-tauri/src/proxy/server.rs

@@ -10,7 +10,8 @@
 
 use super::{
     failover_switch::FailoverSwitchManager, handlers, log_codes::srv as log_srv,
-    provider_router::ProviderRouter, types::*, ProxyError,
+    provider_router::ProviderRouter, providers::gemini_shadow::GeminiShadowStore, types::*,
+    ProxyError,
 };
 use crate::database::Database;
 use axum::{
@@ -36,6 +37,8 @@ pub struct ProxyState {
     pub current_providers: Arc<RwLock<std::collections::HashMap<String, (String, String)>>>,
     /// 共享的 ProviderRouter（持有熔断器状态，跨请求保持）
     pub provider_router: Arc<ProviderRouter>,
+    /// Gemini Native shadow state，用于 thoughtSignature / tool call 回放
+    pub gemini_shadow: Arc<GeminiShadowStore>,
     /// AppHandle，用于发射事件和更新托盘菜单
     pub app_handle: Option<tauri::AppHandle>,
     /// 故障转移切换管理器
@@ -69,6 +72,7 @@ impl ProxyServer {
             start_time: Arc::new(RwLock::new(None)),
             current_providers: Arc::new(RwLock::new(std::collections::HashMap::new())),
             provider_router,
+            gemini_shadow: Arc::new(GeminiShadowStore::default()),
             app_handle,
             failover_manager,
         };