feat(settings): add admin settings UI and Navbar link

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

app/components/Navbar.tsx

@@ -25,6 +25,12 @@ export default function Navbar() {
           >
             Analyze
           </Link>
+          {/* If you have an isAdmin helper, show Settings only for admins. Example:
+              {isAdmin(user) && (
+                <Link to="/settings" className="text-gray-600 hover:text-blue-600 font-medium transition-colors">Settings</Link>
+              )}
+          */}
+          <a href="/settings" className="text-gray-600 hover:text-blue-600 font-medium transition-colors">Settings</a>
         </div>
       </div>
     </nav>

app/routes/settings.tsx

@@ -0,0 +1,61 @@
+import type { LoaderFunction } from '@remix-run/node';
+import { json } from '@remix-run/node';
+import React, { useEffect, useState } from 'react';
+import { requireAdmin } from '~/lib/auth.server';
+import { settingsService } from '~/lib/settings.server';
+
+export const loader: LoaderFunction = async ({ request }) => {
+  await requireAdmin(request);
+  await settingsService.init?.();
+  const entries: any[] = [];
+  // @ts-ignore
+  for (const key of (settingsService as any).cache.keys()) {
+    entries.push({ key, value: await settingsService.get(key) });
+  }
+  return json({ entries });
+};
+
+export default function SettingsPage() {
+  const [items, setItems] = useState<Array<{ key: string; value: any }>>([]);
+  useEffect(() => {
+    fetch('/api/admin/settings')
+      .then(r => r.json())
+      .then(j => setItems(j));
+  }, []);
+
+  async function save(key: string, value: any) {
+    await fetch(`/api/admin/settings/${encodeURIComponent(key)}`, {
+      method: 'PUT',
+      headers: { 'content-type': 'application/json' },
+      body: JSON.stringify({ value }),
+    });
+    setItems(s => s.map(i => (i.key === key ? { ...i, value } : i)));
+  }
+
+  return (
+    <div className="p-6">
+      <h1 className="text-2xl font-bold mb-4">Settings</h1>
+      <ul>
+        {items.map(it => (
+          <li key={it.key} className="mb-3">
+            <div className="flex items-center gap-4">
+              <div className="font-medium">{it.key}</div>
+              <textarea
+                className="border p-2 w-2/3"
+                defaultValue={JSON.stringify(it.value, null, 2)}
+                onBlur={e => {
+                  try {
+                    const v = JSON.parse(e.currentTarget.value);
+                    save(it.key, v);
+                  } catch (err) {
+                    alert('Invalid JSON');
+                  }
+                }}
+              />
+            </div>
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}