Enhance custom.js to prompt for API key if missing and inject script tag

assets/custom.js

@@ -1,6 +1,15 @@
-// Auto‑load saved image generation API key into the MCP input field
+// Auto‑load saved image‑generation API key into the MCP input field.
+// If no key is stored, prompt the user once and persist it in localStorage.
 window.addEventListener('load', () => {
-  const savedKey = localStorage.getItem('image_api_key');
+  const storageKey = 'image_api_key';
+  let savedKey = localStorage.getItem(storageKey);
+  if (!savedKey) {
+    // Prompt user only once per browser session
+    savedKey = prompt('Enter your Inference Co‑op image‑generation API key (will be saved locally):');
+    if (savedKey) {
+      localStorage.setItem(storageKey, savedKey);
+    }
+  }
   if (savedKey) {
     const icInput = document.querySelector('input[name="IC_API_KEY"]');
     if (icInput) icInput.value = savedKey;