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

backend/src/middleware/nip98.ts

@@ -83,8 +83,8 @@ export async function nip98Auth(req: Request, res: Response, next: NextFunction)
   }
 
   // Reconstruct absolute URL (protocol + host + path + query)
-  const proto = req.headers["x-forwarded-proto"] ?? (req.socket as { encrypted?: boolean }).encrypted ? "https" : "http";
-  const host = req.headers["x-forwarded-host"] ?? req.headers.host ?? "";
+  const proto = (req.headers["x-forwarded-proto"] as string | undefined) ?? ((req.socket as { encrypted?: boolean }).encrypted ? "https" : "http");
+  const host = (req.headers["x-forwarded-host"] as string | undefined) ?? req.headers.host ?? "";
   const path = req.originalUrl ?? req.url;
   const absoluteUrl = `${proto}://${host}${path}`;
   if (u !== absoluteUrl) {