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

docs/overview.md

@@ -110,14 +110,27 @@ After installation, access the management interface at `https://<hostname>.local
 │   │   ├── wireguard.py     # WireGuard API
 │   │   ├── network.py       # Networkd API
 │   │   └── logs.py          # Logs API
-│   └── static/              # SPA (index.html, app.js, reactive-dom.js, style.css)
+│   └── static/              # SPA (index.html, app.js, style.css)
+│       ├── hoover/          # Hoover SPA framework (VDOM, reactivity, router, components)
+│       │   ├── index.js     # Barrel export of all public APIs
+│       │   ├── reactivity.js
+│       │   ├── vdom.js
+│       │   ├── render.js
+│       │   ├── component.js
+│       │   ├── router.js
+│       │   ├── websocket.js
+│       │   ├── api.js
+│       │   ├── helpers.js
+│       │   └── components/  # Layout, data display, modal, toast
+│       └── pages/           # Page modules (each defines a route via definePage)
 ├── docs/                    # Documentation
 │   ├── overview.md          # This file
 │   ├── deployment.md
 │   ├── api.md
 │   ├── security.md
 │   ├── architecture.md
-│   └── config.md
+│   ├── config.md
+│   └── hoover.md            # Hoover SPA framework
 └── scripts/                   # Utility scripts
     └── update-vendor.sh      # Vendor frontend library updates
 ```
@@ -129,3 +142,4 @@ After installation, access the management interface at `https://<hostname>.local
 - [Security Model](security.md) - Privilege model and sudo whitelist
 - [Architecture](architecture.md) - Detailed subsystem design
 - [Configuration](config.md) - Config file formats and locations
+- [Hoover Framework](hoover.md) - Frontend SPA framework reference