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/bans/page.tsx

@@ -1,6 +1,7 @@
 import { createBan, liftBan } from "@/actions/admin-bans";
 import { StatusCard } from "@/components/admin/dashboard";
 import { prisma } from "@/lib/prisma";
+import { Ban } from "lucide-react";
 
 export const dynamic = "force-dynamic";
 
@@ -27,10 +28,15 @@ export default async function AdminBans() {
 
   return (
     <main>
-      <h1>Bans</h1>
-      <p className="muted" style={{ marginTop: "-0.4rem" }}>
-        Active bans only (expiry in the future) · 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">
+          <Ban size={20} className="text-[var(--color-primary)]" />
+        </div>
+        <div>
+          <h1 className="m-0 text-xl font-extrabold text-[var(--color-text)]">Bans</h1>
+          <p className="m-0 text-xs text-[var(--color-text-muted)] mt-0.5">Active bans only (expiry in the future) · newest first.</p>
+        </div>
+      </div>
 
       <div className="grid grid-cols-[repeat(auto-fit,minmax(180px,1fr))] gap-3.5 mb-6">
         <StatusCard
@@ -48,9 +54,9 @@ export default async function AdminBans() {
         <StatusCard label="Account bans" value={accountBans} icon="👤" />
       </div>
 
-      <form action={createBan} className="card" style={{ marginBottom: "1.5rem" }}>
-        <h3 style={{ marginTop: 0 }}>New ban</h3>
-        <div style={{ display: "flex", gap: "0.5rem", flexWrap: "wrap" }}>
+      <form action={createBan} className="admin-card mb-6">
+        <h3 className="text-sm font-bold text-[var(--color-text)] m-0 mb-3">New ban</h3>
+        <div className="flex gap-2 flex-wrap">
           <input name="userId" type="number" min={1} placeholder="User ID" required />
           <select name="type">
             <option value="account">account</option>
@@ -59,7 +65,7 @@ export default async function AdminBans() {
             <option value="super">super</option>
           </select>
           <input name="hours" type="number" min={0} placeholder="Hours (0 = perm)" />
-          <input name="reason" placeholder="Reason" style={{ flex: 1, minWidth: 160 }} />
+          <input name="reason" placeholder="Reason" className="flex-1 min-w-[160px]" />
           <button type="submit" className="btn btn-danger">
             Ban
           </button>
@@ -67,11 +73,11 @@ export default async function AdminBans() {
       </form>
 
       <section className="mt-6">
-        <h2>Active bans ({bans.length})</h2>
+        <h2 className="admin-section-title">Active bans ({bans.length})</h2>
         {bans.length === 0 ? (
-          <p className="muted">No active bans.</p>
+          <div className="admin-empty">No active bans.</div>
         ) : (
-          <div style={{ overflowX: "auto" }}>
+          <div className="overflow-x-auto">
             <table>
               <thead>
                 <tr>
@@ -94,7 +100,7 @@ export default async function AdminBans() {
                       {b.banExpire === 0 ? (
                         <span className="inline-block text-[0.72rem] font-bold px-2 py-0.5 rounded-full bg-red-500/22 text-[var(--color-text)]">permanent</span>
                       ) : (
-                        <span className="muted" style={{ whiteSpace: "nowrap" }}>
+                        <span className="text-sm text-gray-500 dark:text-gray-400 whitespace-nowrap">
                           {fromUnix(b.banExpire)}
                         </span>
                       )}