Safety screens: followers, blocking, reporting, admin

Web and mobile:
- Follower/following lists (tap the counts), with Follow buttons and
  "Remove" on your own followers.
- Profile ⋯ menu: block (with confirmation) / unblock, and report with a
  reason and optional note. "Follows you" label, "Follow back", and a
  banner on profiles you've blocked.
- Blocked accounts list in Settings, with unblock.
Web only: /admin for the admin account: stats, open/resolved reports,
resolve, suspend/unsuspend.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/web/src/components/Nav.tsx

@@ -26,6 +26,7 @@ export function Nav() {
             <Link href="/">Feed</Link>
             <Link href={`/u/${me.username}`}>Profile</Link>
             <Link href="/settings">Settings</Link>
+            {me.role === 'admin' && <Link href="/admin">Admin</Link>}
             <button className="link-button" onClick={logout}>
               Log out
             </button>