SIWE auth, API proxy fixes, dashboard, login, usage pages

- SIWE auth flow: challenge/login/logout/me API routes + JWT middleware
- Fixed [...path] catch-all: Kubo proxy with matchRoute() + mapToKuboAPI()
- Fixed session_id → nonce field mismatch in AuthProvider
- Fixed dashboard pins crash: Kubo returns {Keys: {...}}, not array
- Added middleware route guard (307 redirect to /login)
- Added login, register, profile, usage, upload pages
- Added dashboard components (StorageGauge, FreeTierProgress)
- Added SWR hooks + AuthGuard + Providers + Toast/ErrorBoundary
- Added payment integration (smart contract ABI, tiers, tokens)
- Fixed IPNS key listing: Name/Id → name/id mapping
- Added PWA support (manifest, service worker, icons)
- Added tests for helpers, limits, search-index, wallet

scripts/gen-icons.cjs

@@ -0,0 +1,18 @@
+/* ── Generate PNG icons from SVG ── */
+const sharp = require('sharp');
+const fs = require('fs');
+const path = require('path');
+
+async function main() {
+  const sizes = [192, 512];
+  for (const size of sizes) {
+    const svg = fs.readFileSync(path.join(__dirname, '..', 'public', 'icon-' + size + '.svg'));
+    await sharp(svg)
+      .resize(size, size)
+      .png()
+      .toFile(path.join(__dirname, 'icon-' + size + '.png'));
+    console.log(`Generated icon-${size}.png`);
+  }
+}
+
+main().catch(console.error);