feat: add configurable payments and Gitea staging delivery

Add database-backed administrators, configurable Alipay packages, idempotent payment settlement and platform reporting. Standardize Gitea workflows on the xiaoxin runner so reviewed staging commits are tested, packaged, and deployed by immutable image digest.

frontend/src/lib/supabase/admin.ts

@@ -36,3 +36,22 @@ export function isAdminEmail(email: string | null | undefined) {
     .split(",")
     .some((candidate) => candidate.trim().toLowerCase() === normalized);
 }
+
+export async function isAdminUser(user: { id?: string | null; email?: string | null } | null | undefined) {
+  if (!user?.email) return false;
+  if (isAdminEmail(user.email)) return true;
+  if (process.env.AUTH_PROVIDER?.trim() === "self-hosted" || !user.id) return false;
+
+  try {
+    const admin = createAdminSupabaseClient();
+    const { data, error } = await admin
+      .from("admin_users")
+      .select("user_id")
+      .eq("user_id", user.id)
+      .is("revoked_at", null)
+      .maybeSingle();
+    return !error && Boolean(data);
+  } catch {
+    return false;
+  }
+}