refactor: modernize frontend with hoover framework components and docs

- Add quick modal, table, service status, and confirmation dialog components
- Refactor all pages (certs, dhcp, proxy, etc.) to use new component patterns
- Introduce refactor load utility and render guard for consistent UX
- Add hoover documentation and update AGENTS.md, architecture, overview

AGENTS.md

@@ -41,7 +41,17 @@ Project uses `.venv`. Install deps with `pip install -e .` (from `pyproject.toml
 
 ### Frontend (hoover)
 
-Custom reactive SPA framework at `webui/static/hoover/`. Provides VDOM rendering, reactivity, router, WebSocket bindings, API helpers, and shared UI components. Exported via `hoover/index.js`. Pages in `webui/static/pages/` each define a route using `definePage()`. Bootstrap is `webui/static/app.js`. No build step — served raw.
+Custom reactive SPA framework at `webui/static/hoover/`. See `docs/hoover.md` for full API reference.
+
+Conventions:
+- All imports from `/static/hoover/index.js` (barrel export of reactivity, VDOM, router, API, components).
+- Pages in `webui/static/pages/` export `definePage({ init, subscribe, load, render })` as default.
+- Bootstrap: `webui/static/app.js` mounts two render roots (`#sidebar`, `#main`), then `connect()` for WS.
+- `h()` builds VNodes; `#comp` + `hComp()` for component lifecycle; `key` for keyed diff.
+- Events use `on:` prefix (`on:click`, `on:submit`). `class` prop accepts object.
+- State always has `loading`, `refreshing`, `error` plus data. `load()` receives `(state, abortController, entry)`.
+- `openModal` + `formModal` for dialogs; `apiSubmit()` for form submission. `ToastContainer()` in main root.
+- No build step — ES modules served raw. Assets versioned via `?v=N` query string.
 
 ### Daemon Endpoints