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/app/(site)/shop/loading.tsx

@@ -0,0 +1,15 @@
+export default function ShopLoading() {
+	return (
+		<div
+			style={{ display: "flex", justifyContent: "center", padding: "4rem 0" }}
+		>
+			<div
+				className="animate-spin w-8 h-8 border-4 rounded-full"
+				style={{
+					borderColor: "var(--color-primary)",
+					borderTopColor: "transparent",
+				}}
+			/>
+		</div>
+	);
+}