Remove query-string cache-busting from static assets

Drop ?v=N version pins from all JS imports and HTML <link>/<script> tags.
Cache invalidation is now handled solely by server-side cache-control headers.
Update docs and AGENTS.md accordingly.

webui/static/hoover/websocket.js

@@ -6,8 +6,8 @@
  * Page-level subscribe/unsubscribe is replaced by the model layer.
  */
 
-import { refreshByTopic } from './model.js?v=9';
-import { tryRefreshToken, redirectLogin } from './api.js?v=12';
+import { refreshByTopic } from './model.js';
+import { tryRefreshToken, redirectLogin } from './api.js';
 
 let _wsConn = null;
 let _wsReconnectMs = 0;