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

src/lib/components/icons/IconFile.svelte

@@ -2,9 +2,29 @@
 </script>
 
 <svg width="23" height="24" viewBox="0 0 23 24" fill="none" xmlns="http://www.w3.org/2000/svg">
-    <path fill-rule="evenodd" clip-rule="evenodd" d="M18.6875 19.7575C18.6875 21.0807 17.6148 22.1533 16.2917 22.1533H4.3125V5.99287C4.3125 5.39212 4.54755 4.81522 4.96738 4.38552L7.17097 2.13015C7.60374 1.68721 8.19683 1.4375 8.81609 1.4375H16.3875C17.6578 1.4375 18.6875 2.46725 18.6875 3.7375V19.7575Z" stroke="currentColor" stroke-width="1.86875"/>
-    <path d="M7.06787 12.5889H15.6929" stroke="currentColor" stroke-width="1.725" stroke-linecap="round"/>
-    <path d="M7.06787 8.71875H15.6929" stroke="currentColor" stroke-width="1.725" stroke-linecap="round"/>
-    <path d="M7.06787 16.464H12.8179" stroke="currentColor" stroke-width="1.725" stroke-linecap="round"/>
+	<path
+		fill-rule="evenodd"
+		clip-rule="evenodd"
+		d="M18.6875 19.7575C18.6875 21.0807 17.6148 22.1533 16.2917 22.1533H4.3125V5.99287C4.3125 5.39212 4.54755 4.81522 4.96738 4.38552L7.17097 2.13015C7.60374 1.68721 8.19683 1.4375 8.81609 1.4375H16.3875C17.6578 1.4375 18.6875 2.46725 18.6875 3.7375V19.7575Z"
+		stroke="currentColor"
+		stroke-width="1.86875"
+	/>
+	<path
+		d="M7.06787 12.5889H15.6929"
+		stroke="currentColor"
+		stroke-width="1.725"
+		stroke-linecap="round"
+	/>
+	<path
+		d="M7.06787 8.71875H15.6929"
+		stroke="currentColor"
+		stroke-width="1.725"
+		stroke-linecap="round"
+	/>
+	<path
+		d="M7.06787 16.464H12.8179"
+		stroke="currentColor"
+		stroke-width="1.725"
+		stroke-linecap="round"
+	/>
 </svg>
-