Feature: Multi-email alerts and move resource between groups

- notificationService: Parse comma-separated emails from resource.email_to or global config; validate and send to each recipient
- API: Add PATCH /api/resources/:id/group endpoint to move resource between groups with validation and cache invalidation
- UI: Add group selector to edit modal; wire group change to PATCH endpoint; add help text for multi-email format

client/build/asset-manifest.json

@@ -1,15 +1,15 @@
 {
   "files": {
     "main.css": "/static/css/main.2e6b09f5.css",
-    "main.js": "/static/js/main.9a96e479.js",
+    "main.js": "/static/js/main.b7b055d1.js",
     "static/js/453.d456ce70.chunk.js": "/static/js/453.d456ce70.chunk.js",
     "index.html": "/index.html",
     "main.2e6b09f5.css.map": "/static/css/main.2e6b09f5.css.map",
-    "main.9a96e479.js.map": "/static/js/main.9a96e479.js.map",
+    "main.b7b055d1.js.map": "/static/js/main.b7b055d1.js.map",
     "453.d456ce70.chunk.js.map": "/static/js/453.d456ce70.chunk.js.map"
   },
   "entrypoints": [
     "static/css/main.2e6b09f5.css",
-    "static/js/main.9a96e479.js"
+    "static/js/main.b7b055d1.js"
   ]
 }