feat(ui): add PWA support with vite-plugin-pwa

- Add vite.config.pwa.ts extending the base config with VitePWA plugin
- Generate PWA icons at build time from source logo via @vite-pwa/assets-generator
- Add web app manifest with name, theme color, display overrides
- Add Workbox runtime caching: NetworkFirst for API, CacheFirst for assets
- Set navigateFallback to null to preserve server-side auth redirects
- Server build uses build:pwa for PWA-enabled output; Electron/Tauri use
  the base build without PWA

Signed-off-by: Jesper Derehag <jderehag@hotmail.com>

packages/server/README.md

@@ -62,6 +62,17 @@ You can configure the server using flags or environment variables:
   Use this only when access is already protected by another layer (SSO proxy, VPN, Coder workspace auth, etc.).
   If you bind to `0.0.0.0` while skipping auth, anyone who can reach the port can access the API.
 
+### Progressive Web App (PWA)
+When running as a server CodeNomad can also be installed as a PWA from any supported browser, giving you a native app experience just like the Electron installation but executing on the remote server instead.
+
+1. Open the CodeNomad UI in a Chromium-based browser (Chrome, Edge, Brave, etc.).
+2. Click the install icon in the address bar, or use the browser menu → "Install CodeNomad".
+3. The app will open in a standalone window and appear in your OS app list.
+
+> **TLS requirement**
+> Browsers require a secure (`https://`) connection for PWA installation.
+> If you host CodeNomad on a remote machine, serve it behind a reverse proxy (e.g. Caddy, nginx) with a valid TLS certificate — self-signed certificates will not work.
+
 ### Data Storage
 - **Config**: `~/.config/codenomad/config.json`
 - **Instance Data**: `~/.config/codenomad/instances` (chat history, etc.)