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.

AGENTS.md

@@ -54,7 +54,7 @@ Conventions:
 - `h()` builds VNodes with `on:click` prefix. `html` tag (htm) templates use camelCase `onClick` (adapter translates).
 - State always has `loading`, `refreshing`, `error` plus data. `load()` receives `(state, abortController, entry)`.
 - `openModal` + `formModal` for dialogs; `apiSubmit()` for form submission.
-- No build step — ES modules served raw. Assets versioned via `?v=N` query string.
+- No build step — ES modules served raw. Cache controlled via HTTP headers.
 
 ### Daemon Endpoints