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/pages/dashboard.js

@@ -1,4 +1,4 @@
-import { html, PageHeader, definePage, getModel, renderGuardMulti, ServiceStatus, StatCard, Table, Badge, ActionButton } from '/static/hoover/index.js?v=11';
+import { html, PageHeader, definePage, getModel, renderGuardMulti, ServiceStatus, StatCard, Table, Badge, ActionButton } from '/static/hoover/index.js';
 
 function fmtBytes(bytes) {
     if (bytes === 0) return '0 B';