feat: shop buy, forum replies, tickets, messages, sessions, and UX hardening

Complete remaining product gaps: credit-based shop purchases, guild thread replies, help ticket detail/reply/close, offline message compose, sign-out-everywhere via JWT version, ads delete confirm, soft-fail feedback, rate limits, loading states, and single auth() in site layout.

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

src/types/next-auth.d.ts

@@ -9,5 +9,7 @@ declare module "next-auth" {
 declare module "next-auth/jwt" {
 	interface JWT {
 		rank?: number;
+		jwtVersion?: number;
+		invalid?: boolean;
 	}
 }