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/IconChain.svelte

@@ -2,7 +2,17 @@
 </script>
 
 <svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
-    <path d="M10.5618 6.94745L14.1001 3.31245C15.0133 2.37424 16.5206 2.37424 17.4338 3.31245L19.0544 4.97737C19.9334 5.88045 19.9334 7.31929 19.0544 8.22237L14.3368 13.069C13.4235 14.0072 11.9162 14.0072 11.003 13.069L10.5537 12.6075" stroke="currentColor" stroke-width="1.9" stroke-linecap="round" stroke-linejoin="round"/>
-    <path d="M12.8717 16.4126L7.66659 21.76L4.37911 18.3826C3.50007 17.4796 3.50008 16.0407 4.37911 15.1376L9.09675 10.291C10.01 9.35276 11.5173 9.35276 12.4305 10.291L12.8798 10.7525" stroke="currentColor" stroke-width="1.9" stroke-linecap="round"/>
+	<path
+		d="M10.5618 6.94745L14.1001 3.31245C15.0133 2.37424 16.5206 2.37424 17.4338 3.31245L19.0544 4.97737C19.9334 5.88045 19.9334 7.31929 19.0544 8.22237L14.3368 13.069C13.4235 14.0072 11.9162 14.0072 11.003 13.069L10.5537 12.6075"
+		stroke="currentColor"
+		stroke-width="1.9"
+		stroke-linecap="round"
+		stroke-linejoin="round"
+	/>
+	<path
+		d="M12.8717 16.4126L7.66659 21.76L4.37911 18.3826C3.50007 17.4796 3.50008 16.0407 4.37911 15.1376L9.09675 10.291C10.01 9.35276 11.5173 9.35276 12.4305 10.291L12.8798 10.7525"
+		stroke="currentColor"
+		stroke-width="1.9"
+		stroke-linecap="round"
+	/>
 </svg>
-