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/components/auth.js

@@ -4,7 +4,7 @@
  * Token refresh scheduler, session check, logout.
  */
 
-import { apiFetch, setAuthToken, clearAuthTokens, redirectLogin, getAuthToken, tryRefreshToken, toast } from '../api.js?v=12';
+import { apiFetch, setAuthToken, clearAuthTokens, redirectLogin, getAuthToken, tryRefreshToken, toast } from '../api.js';
 
 /**
  * Schedule a token refresh based on the access token TTL stored in sessionStorage.