fix: 修复所有 abort() 不传 reason 导致的'signal is aborted without reason'提示

为 llm.js/embedding.js/vector-index.js/index.js 中所有
controller.abort() 添加具体原因:
- 超时: 'LLM 请求超时 (60s)' / 'Embedding 请求超时 (45s)'
- 信号传递: 转发原始 signal.reason

vector-index.js

@@ -79,17 +79,17 @@ function createCombinedAbortSignal(...signals) {
   const controller = new AbortController();
   for (const signal of validSignals) {
     if (signal.aborted) {
-      controller.abort();
+      controller.abort(signal.reason);
       return controller.signal;
     }
-    signal.addEventListener("abort", () => controller.abort(), { once: true });
+    signal.addEventListener("abort", () => controller.abort(signal.reason), { once: true });
   }
   return controller.signal;
 }
 
 async function fetchWithTimeout(url, options = {}, timeoutMs = VECTOR_REQUEST_TIMEOUT_MS) {
   const controller = new AbortController();
-  const timeout = setTimeout(() => controller.abort(), timeoutMs);
+  const timeout = setTimeout(() => controller.abort(new DOMException(`向量请求超时 (${Math.round(timeoutMs / 1000)}s)`, 'AbortError')), timeoutMs);
   const signal = options.signal
     ? createCombinedAbortSignal(options.signal, controller.signal)
     : controller.signal;