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/html.js

@@ -1,4 +1,4 @@
 import htm from '../../vendor/htm.js';
-import { htmAdapter } from './vdom.js?v=9';
+import { htmAdapter } from './vdom.js';
 
 export const html = htm.bind(htmAdapter);