🤖 Fix service worker cache errors for POST requests

Service worker was attempting to cache all requests including POST
requests (from browser mode IPC calls and AI streaming). The Cache API
only supports caching GET requests.

Added check to skip caching for non-GET requests, preventing the error:
'Failed to execute 'put' on 'Cache': Request method 'POST' is unsupported'

This fix maintains PWA caching for browser mode while avoiding errors
during development and when using POST-based features.

Author: ammar-agent

public/service-worker.js

@@ -33,6 +33,13 @@ self.addEventListener('activate', (event) => {
 
 // Fetch event - network first, fallback to cache
 self.addEventListener('fetch', (event) => {
+  // Skip caching for non-GET requests (POST, PUT, DELETE, etc.)
+  // The Cache API only supports GET requests
+  if (event.request.method !== 'GET') {
+    event.respondWith(fetch(event.request));
+    return;
+  }
+
   event.respondWith(
     fetch(event.request)
       .then((response) => {