Refactor admin UI for consolidated navigation and improved moderation workflow

- Updated Sidebar component to consolidate navigation items under new categories: Moderation, Content, and Operations.
- Removed outdated pages and integrated their functionalities into tabs under Players, Activity, Content, and Settings.
- Introduced new Activity and Content pages to house Audit, Player Logs, Community Board, and Loading Tips with tabbed navigation.
- Created a unified Moderation page combining Players, Bans, and Reports with tabbed navigation.
- Refactored individual pages (e.g., Audit, Bans, CommunityBoard, etc.) to support embedded mode for better integration within modals.
- Added Tabs component for consistent tab navigation across multiple pages.
- Updated README to reflect changes in navigation and settings structure.
- Removed Grants page as it is not yet implemented.

DorkNet.Server/admin-ui/src/pages/Activity.tsx

@@ -0,0 +1,25 @@
+import { Audit } from './Audit';
+import { PlayerLogs } from './PlayerLogs';
+import { PageHeader } from '../components/PageHeader';
+import { Tabs, useTabParam } from '../components/Tabs';
+
+// Both log views in one place: the admin audit trail and the per-player
+// HTTP request ring buffer. Old /audit and /logs routes redirect here.
+export function Activity() {
+  const [tab, setTab] = useTabParam<'audit' | 'logs'>('audit', ['audit', 'logs']);
+  return (
+    <div>
+      <PageHeader title="Activity" blurb="Admin audit trail and per-player HTTP request logs." />
+      <Tabs
+        tabs={[
+          { key: 'audit', label: 'Audit log' },
+          { key: 'logs', label: 'Player requests' },
+        ]}
+        active={tab}
+        onChange={setTab}
+      />
+      {tab === 'audit' && <Audit embedded />}
+      {tab === 'logs' && <PlayerLogs embedded />}
+    </div>
+  );
+}