feat(claude-desktop): add 3P provider switching with proxy gateway

Adds a new ClaudeDesktop AppType that writes Claude Desktop's third-party
inference profile under configLibrary/, sharing _meta.json with other
launchers (Ollama-compatible) so cc-switch can coexist with them.

Two switch modes:
- direct: provider already exposes claude-* / anthropic/claude-* model
  ids on Anthropic Messages, Claude Desktop connects to it directly.
- proxy: cc-switch's local proxy acts as the inference gateway,
  presenting only claude-* route names to Claude Desktop and mapping
  them to real upstream models. Required after Anthropic restricted
  Claude Desktop to claude-family ids.

Backend:
- New module claude_desktop_config with snapshot/rollback, official seed
  bypass, /claude-desktop/v1/{models,messages} routes, and a single
  source of truth for default proxy routes.
- Gateway token persisted in SQLite, validated on every proxied request.
- get_claude_desktop_status surfaces drift signals (stale models,
  missing routes, proxy stopped, base URL mismatch, missing token).

Frontend:
- Slim ClaudeDesktopProviderForm independent from ProviderForm,
  controlled by a top-level appId guard.
- ProviderList banner consumes the status query (5s polling) and
  renders actionable diagnostics.
- ClaudeDesktopRouteToggle in the header to start/stop the local
  gateway without touching takeover state.
- Three-locale i18n synchronised.

src-tauri/src/proxy/providers/claude.rs

@@ -380,6 +380,16 @@ impl ClaudeAdapter {
                 log::debug!("[Claude] 使用 OPENAI_API_KEY");
                 return Some(key.to_string());
             }
+            // Gemini Native key
+            if let Some(key) = env
+                .get("GEMINI_API_KEY")
+                .and_then(|v| v.as_str())
+                .map(str::trim)
+                .filter(|s| !s.is_empty())
+            {
+                log::debug!("[Claude] 使用 GEMINI_API_KEY");
+                return Some(key.to_string());
+            }
         }
 
         // 尝试直接获取
@@ -904,6 +914,27 @@ mod tests {
         assert_eq!(auth.strategy, AuthStrategy::Bearer);
     }
 
+    #[test]
+    fn test_extract_auth_gemini_api_key() {
+        let adapter = ClaudeAdapter::new();
+        let provider = create_provider_with_meta(
+            json!({
+                "env": {
+                    "ANTHROPIC_BASE_URL": "https://generativelanguage.googleapis.com/v1beta",
+                    "GEMINI_API_KEY": "gemini-test-key"
+                }
+            }),
+            ProviderMeta {
+                api_format: Some("gemini_native".to_string()),
+                ..Default::default()
+            },
+        );
+
+        let auth = adapter.extract_auth(&provider).unwrap();
+        assert_eq!(auth.api_key, "gemini-test-key");
+        assert_eq!(auth.strategy, AuthStrategy::Google);
+    }
+
     #[test]
     fn test_extract_auth_claude_auth_mode() {
         let adapter = ClaudeAdapter::new();

src-tauri/src/proxy/providers/mod.rs

@@ -105,7 +105,7 @@ impl ProviderType {
     #[allow(dead_code)]
     pub fn from_app_type_and_config(app_type: &AppType, provider: &Provider) -> Self {
         match app_type {
-            AppType::Claude => {
+            AppType::Claude | AppType::ClaudeDesktop => {
                 if get_claude_api_format(provider) == "gemini_native" {
                     let adapter = ClaudeAdapter::new();
                     return match adapter.extract_auth(provider).map(|auth| auth.strategy) {
@@ -226,7 +226,7 @@ impl std::str::FromStr for ProviderType {
 /// 根据 AppType 获取对应的适配器
 pub fn get_adapter(app_type: &AppType) -> Box<dyn ProviderAdapter> {
     match app_type {
-        AppType::Claude => Box::new(ClaudeAdapter::new()),
+        AppType::Claude | AppType::ClaudeDesktop => Box::new(ClaudeAdapter::new()),
         AppType::Codex => Box::new(CodexAdapter::new()),
         AppType::Gemini => Box::new(GeminiAdapter::new()),
         AppType::OpenCode | AppType::OpenClaw | AppType::Hermes => {