fix: add { once: true } to abort listeners, use ApiError for retry exhaustion

- combineSignals in MLXProvider, OllamaProvider, and OpenRouterClient now
  passes { once: true } to addEventListener so abort listeners are
  automatically removed after firing, preventing listener leaks.
- OpenRouterClient retry-exhaustion fallback now throws ApiError instead of
  plain Error so callers receive a typed, retryable-flagged error.

Author: igorcosta

src/providers/MLXProvider.ts

@@ -318,8 +318,8 @@ export class MLXProvider implements LLMProvider {
     private combineSignals(signal1: AbortSignal, signal2: AbortSignal): AbortSignal {
         const controller = new AbortController();
         const abort = () => controller.abort();
-        signal1.addEventListener('abort', abort);
-        signal2.addEventListener('abort', abort);
+        signal1.addEventListener('abort', abort, { once: true });
+        signal2.addEventListener('abort', abort, { once: true });
         if (signal1.aborted || signal2.aborted) {
             controller.abort();
         }

src/providers/OllamaProvider.ts

@@ -463,8 +463,8 @@ export class OllamaProvider implements LLMProvider {
     private combineSignals(signal1: AbortSignal, signal2: AbortSignal): AbortSignal {
         const controller = new AbortController();
         const abort = () => controller.abort();
-        signal1.addEventListener('abort', abort);
-        signal2.addEventListener('abort', abort);
+        signal1.addEventListener('abort', abort, { once: true });
+        signal2.addEventListener('abort', abort, { once: true });
         if (signal1.aborted || signal2.aborted) {
             controller.abort();
         }

src/providers/OpenRouterClient.ts

@@ -194,7 +194,7 @@ export class OpenRouterClient {
     // All retries exhausted
     throw (
       lastError ??
-      new Error("Failed to communicate with the AI service. Please try again.")
+      new ApiError("Failed to communicate with the AI service. Please try again.", 'network_error', 0, true)
     );
   }
 
@@ -340,8 +340,8 @@ export class OpenRouterClient {
     const controller = new AbortController();
 
     const abort = () => controller.abort();
-    signal1.addEventListener("abort", abort);
-    signal2.addEventListener("abort", abort);
+    signal1.addEventListener("abort", abort, { once: true });
+    signal2.addEventListener("abort", abort, { once: true });
 
     if (signal1.aborted || signal2.aborted) {
       controller.abort();