fix: resolve PWA freeze caused by infinite microtask loop in sync.ts and hung fetches without timeout

client/src/services/api.ts

@@ -10,22 +10,43 @@ export class ApiError extends Error {
 
 export async function apiFetch(
   input: string,
-  init: RequestInit = {}
+  init: RequestInit = {},
+  timeoutMs = 15000
 ): Promise<Response> {
   const headers = new Headers(init.headers)
   if (init.body !== undefined && !headers.has('Content-Type')) {
     headers.set('Content-Type', 'application/json')
   }
 
-  return fetch(input, {
-    ...init,
-    headers,
-    credentials: 'include'
-  })
+  const controller = new AbortController()
+  const timeoutId = setTimeout(() => controller.abort(), timeoutMs)
+
+  if (init.signal) {
+    if (init.signal.aborted) {
+      controller.abort()
+    } else {
+      init.signal.addEventListener('abort', () => controller.abort())
+    }
+  }
+
+  try {
+    return await fetch(input, {
+      ...init,
+      headers,
+      credentials: 'include',
+      signal: controller.signal
+    })
+  } finally {
+    clearTimeout(timeoutId)
+  }
 }
 
-export async function apiJson<T>(input: string, init: RequestInit = {}): Promise<T> {
-  const res = await apiFetch(input, init)
+export async function apiJson<T>(
+  input: string,
+  init: RequestInit = {},
+  timeoutMs = 15000
+): Promise<T> {
+  const res = await apiFetch(input, init, timeoutMs)
   const data = await res.json().catch(() => ({}))
   if (!res.ok) {
     const message =