pwa / offline mode

- @vite-pwa/sveltekit: workbox precache (incl. pdfjs worker), generated manifest, prompt-style updates via PwaUpdatePrompt toast
- prerendered routes for offline navigation, PWA icons, theme-color + apple-touch-icon
- pwa offline/update e2e suite (pnpm test:pwa, playwright.pwa.config.ts)
- datenschutz: offline/install section; prettier cleanup of shadcn components

vite.config.ts

@@ -1,5 +1,6 @@
 import tailwindcss from '@tailwindcss/vite';
 import adapter from '@sveltejs/adapter-node';
+import { SvelteKitPWA } from '@vite-pwa/sveltekit';
 import { sveltekit } from '@sveltejs/kit/vite';
 import { defineConfig } from 'vite';
 
@@ -14,6 +15,51 @@ export default defineConfig({
 			},
 
 			adapter: adapter()
+		}),
+		SvelteKitPWA({
+			registerType: 'prompt',
+			injectRegister: false,
+			manifest: {
+				name: 'beA-Edit',
+				short_name: 'beA-Edit',
+				description:
+					'PDF-Werkzeuge für die beA-Kanzlei – PDFs werden vollständig lokal im Browser verarbeitet.',
+				display: 'standalone',
+				orientation: 'any',
+				lang: 'de',
+				dir: 'ltr',
+				start_url: '/',
+				scope: '/',
+				categories: ['productivity', 'utilities'],
+				background_color: '#eef4f6',
+				theme_color: '#122f62',
+				icons: [
+					{ src: '/icons/icon-192.png', sizes: '192x192', type: 'image/png' },
+					{ src: '/icons/icon-512.png', sizes: '512x512', type: 'image/png' },
+					{
+						src: '/icons/icon-maskable-512.png',
+						sizes: '512x512',
+						type: 'image/png',
+						purpose: 'maskable'
+					}
+				]
+			},
+			workbox: {
+				// The plugin prepends `client/` and `prerendered/` paths itself; extending the
+				// default list only adds the local font files and the pdfjs worker chunk (`*.mjs`,
+				// 2.1 MB, required to render PDFs offline). `client/Nunito/**` is the unused font
+				// drop from `static/` and would add 2.6 MB to the precache.
+				globPatterns: ['client/**/*.{js,mjs,css,ico,png,svg,webp,webmanifest,woff2,ttf}'],
+				globIgnores: ['client/Nunito/**'],
+				// Prerendered route documents (see src/routes/+layout.ts) are precached, so an
+				// offline navigation to any visited route — and any unknown path via the
+				// fallback — is served from the cache.
+				navigateFallback: '/',
+				maximumFileSizeToCacheInBytes: 8 * 1024 * 1024
+			},
+			// The service worker is only produced for production builds; `pnpm dev` never
+			// registers one, which keeps development caches clean.
+			devOptions: { enabled: false }
 		})
 	]
 });