fix(proxy): patch P0-P3 routing/lifecycle issues across forwarder paths

* stream_check: thread Result from get_auth_headers via map_err so
  the workspace builds again
* forwarder: scope rectifier / budget-rectifier flags per-provider so
  failover can still apply rectification on the next attempt
* forwarder: categorize before record_result; route NonRetryable and
  ClientAbort through release_permit_neutral so client-side failures
  don't pollute circuit breaker or DB health
* handler_context: parse Gemini model from uri.path() and strip both
  ?query and :action verb defensively in extract_gemini_model_from_path
* forwarder + response_processor + handlers: introduce
  ActiveConnectionGuard (RAII) so active_connections decrement covers
  the full streaming body lifetime, not just response headers
* claude_desktop_config: use sort_by_key to clear the clippy gate

src-tauri/src/proxy/handler_context.rs

@@ -175,10 +175,9 @@ impl RequestContext {
     /// Gemini API 的模型名称在 URI 中，格式如：
     /// `/v1beta/models/gemini-pro:generateContent`
     pub fn with_model_from_uri(mut self, uri: &axum::http::Uri) -> Self {
-        let endpoint = uri
-            .path_and_query()
-            .map(|pq| pq.as_str())
-            .unwrap_or(uri.path());
+        // 用 path() 而不是 path_and_query()：模型名必须从路径段中解析，
+        // 否则 GET /v1beta/models/<id>?key=... 会把 query 拼到 request_model 上。
+        let endpoint = uri.path();
 
         self.request_model =
             extract_gemini_model_from_path(endpoint).unwrap_or_else(|| "unknown".to_string());
@@ -285,6 +284,8 @@ pub(crate) fn extract_gemini_model_from_path(endpoint: &str) -> Option<String> {
         .iter()
         .position(|s| *s == "models")
         .and_then(|i| segments.get(i + 1).copied())
+        // 防御性裁剪：即便调用方传入带 ? 或 :action 的字符串，也只保留 model id 本身
+        .map(|s| s.split('?').next().unwrap_or(s))
         .map(|s| s.split(':').next().unwrap_or(s))
         .filter(|s| !s.is_empty())
         .map(|s| s.to_string())
@@ -347,4 +348,23 @@ mod tests {
         // `/v1beta/models` (list endpoint) has no following segment → None.
         assert_eq!(extract_gemini_model_from_path("/v1beta/models"), None);
     }
+
+    #[test]
+    fn extract_model_get_with_query_only() {
+        // GET /v1beta/models/<id>?key=... 无 action verb，仅靠 ':' 拆分会把 query 带进 model 名。
+        // 修复后应该把 query 剥掉。
+        assert_eq!(
+            extract_gemini_model_from_path("/v1beta/models/gemini-pro?key=abc").as_deref(),
+            Some("gemini-pro"),
+        );
+    }
+
+    #[test]
+    fn extract_model_get_with_proxy_prefix_and_query() {
+        assert_eq!(
+            extract_gemini_model_from_path("/gemini/v1beta/models/gemini-2.0-flash?key=abc")
+                .as_deref(),
+            Some("gemini-2.0-flash"),
+        );
+    }
 }