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

webui/static/hoover/vdom.js

@@ -198,6 +198,7 @@ export function patchUnkeyed(parent, oldCh, newCh) {
             if (d?.parentNode) {
                 if (d.nodeType === Node.ELEMENT_NODE) sweepDom(d);
                 d.parentNode.removeChild(d);
+                lastDom = i > 0 ? getDom(oldCh[i - 1]) : null;
             }
             continue;
         }