feat: jwt cache, redis health, help-ticket admin, and write rate limits

Cut Auth.js DB load with cached jwtVersion checks, surface Redis in /api/health and deploy warnings, add admin help-center ticket reply UI, rate-limit API tickets/reactions/referral claims, and revoke PATs on sign-out-everywhere.

Co-authored-by: Cursor <[email protected]>

src/lib/redis.ts

@@ -16,7 +16,7 @@ function createRedis(): Redis | null {
 		) {
 			globalForRedis.redisMissingWarned = true;
 			console.error(
-				"[redis] REDIS_URL is unset in production. Rate limits and shared caches fall back to in-process memory and will not work correctly across multiple instances.",
+				"[redis] REDIS_URL is unset in production. Rate limits, site-settings cache, and JWT session invalidation fall back to in-process memory and will not work correctly across multiple instances or restarts. Set REDIS_URL in .env.",
 			);
 		}
 		return null;