Convert admin pages to new Tailwind design pattern

- Replace 'card' class with 'admin-card' (gradient cards, dark mode support)
- Replace 'muted' class with consistent Tailwind muted states
- Standardize page headers with gradient backgrounds and Lucide icons
- Convert all inline styles to Tailwind classes
- Add admin-page CSS helpers (admin-card, admin-filter-bar, admin-section-title)
- Apply pattern to all 42 admin pages (was only 6 before)
- Zero TypeScript errors, production builds successfully

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

src/app/admin/transactions/page.tsx

@@ -1,3 +1,4 @@
+import { ArrowLeftRight } from "lucide-react";
 import Link from "next/link";
 import { StatusCard } from "@/components/admin/dashboard";
 import { requireStaff } from "@/lib/admin/guard";
@@ -88,10 +89,15 @@ export default async function AdminTransactions({
 
   return (
     <main>
-      <h1>Transactions</h1>
-      <p className="muted" style={{ marginTop: "-0.4rem" }}>
-        Read-only · PayPal / top-up transactions recorded by the CMS, newest first.
-      </p>
+      <div className="flex items-center gap-3 mb-6">
+        <div className="w-10 h-10 rounded-xl bg-gradient-to-br from-[var(--color-primary)]/20 to-[var(--color-primary)]/5 grid place-items-center">
+          <ArrowLeftRight size={20} className="text-[var(--color-primary)]" />
+        </div>
+        <div>
+          <h1 className="m-0 text-xl font-extrabold text-[var(--color-text)]">Transactions</h1>
+          <p className="m-0 text-xs text-[var(--color-text-muted)] mt-0.5">Read-only · PayPal / top-up transactions recorded by the CMS, newest first.</p>
+        </div>
+      </div>
 
       <div className="grid grid-cols-[repeat(auto-fit,minmax(180px,1fr))] gap-3.5 mb-6">
         <StatusCard label="Total transactions" value={total} icon="🧾" />
@@ -110,11 +116,11 @@ export default async function AdminTransactions({
       </div>
 
       <section className="mt-6">
-        <h2>Transactions ({total})</h2>
+        <h2 className="admin-section-title">Transactions ({total})</h2>
         {transactions.length === 0 ? (
-          <p className="muted">No transactions.</p>
+          <div className="admin-empty">No transactions.</div>
         ) : (
-          <div style={{ overflowX: "auto" }}>
+          <div className="overflow-x-auto">
             <table>
               <thead>
                 <tr>
@@ -132,7 +138,7 @@ export default async function AdminTransactions({
                   const state = statusState(t.status);
                   return (
                     <tr key={String(t.id)}>
-                      <td className="muted">{String(t.id)}</td>
+                      <td className="text-sm text-gray-500 dark:text-gray-400 whitespace-nowrap">{String(t.id)}</td>
                       <td>
                         <Link href={`/admin/users/${t.userId}`}>
                           {names.get(t.userId) ?? `#${t.userId}`}
@@ -148,11 +154,11 @@ export default async function AdminTransactions({
                             {t.status}
                           </span>
                         ) : (
-                          <span className="muted">—</span>
+                          <span className="text-sm text-gray-500 dark:text-gray-400">—</span>
                         )}
                       </td>
-                      <td className="muted">{t.transactionId}</td>
-                      <td className="muted">{fromDate(t.createdAt)}</td>
+                      <td className="text-sm text-gray-500 dark:text-gray-400 whitespace-nowrap">{t.transactionId}</td>
+                      <td className="text-sm text-gray-500 dark:text-gray-400 whitespace-nowrap">{fromDate(t.createdAt)}</td>
                     </tr>
                   );
                 })}
@@ -162,7 +168,7 @@ export default async function AdminTransactions({
         )}
       </section>
 
-      <p className="muted">
+      <p className="text-xs text-gray-500 dark:text-gray-400">
         Page {page} / {pages} · {total} transactions
         {page > 1 ? (
           <>