Production-ready overhaul: backend fixes, claim flow polish, SEO, mobile, nginx

Backend:
- Fix activity score (followersCount check), NIP-98 URL proto, wallet balance guard
- Add payment_hash to confirm response, spentTodaySats to stats
- Add idx_claims_ip_hash; security headers, graceful shutdown, periodic nonce cleanup

Frontend:
- Remove 8 legacy components; polish wizard (rules summary, profile card, confetti, share)
- Stats budget bar uses spentTodaySats; ErrorBoundary with reload

SEO & production:
- Full meta/OG/Twitter, favicon, JSON-LD, robots.txt, sitemap.xml
- Mobile CSS fixes; nginx static dist + gzip + cache + security headers
- Vite manualChunks; aria-labels, dynamic page titles

Made-with: Cursor

frontend/public/sitemap.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+  <url>
+    <loc>https://faucet.lnpulse.app/</loc>
+    <changefreq>daily</changefreq>
+    <priority>1.0</priority>
+  </url>
+  <url>
+    <loc>https://faucet.lnpulse.app/transactions</loc>
+    <changefreq>hourly</changefreq>
+    <priority>0.7</priority>
+  </url>
+</urlset>