fix(web): add Cache-Control: no-store to plugin static file serving

Prevents browser caching of stale dashboard plugin JS files that may
contain bugs already fixed upstream (e.g. COLUMN_LABEL undefined).

hermes_cli/web_server.py

@@ -4346,7 +4346,11 @@ async def serve_plugin_asset(plugin_name: str, file_path: str):
         ".woff": "font/woff",
     }
     media_type = content_types.get(suffix, "application/octet-stream")
-    return FileResponse(target, media_type=media_type)
+    return FileResponse(
+        target,
+        media_type=media_type,
+        headers={"Cache-Control": "no-store, no-cache, must-revalidate"},
+    )
 
 
 def _mount_plugin_api_routes():