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/helpers.js

@@ -49,3 +49,20 @@ export function parseZones(data) {
         z = Object.values(z).map(i => i?.name || i);
     return Array.isArray(z) ? z : [];
 }
+
+/**
+ * Trigger a browser file download from a Blob.
+ *
+ * @param {Blob} blob
+ * @param {string} filename
+ */
+export function downloadBlob(blob, filename) {
+    const url = URL.createObjectURL(blob);
+    const a = document.createElement('a');
+    a.href = url;
+    a.download = filename;
+    document.body.appendChild(a);
+    a.click();
+    document.body.removeChild(a);
+    URL.revokeObjectURL(url);
+}