feat: refactor play area into sidebar layout with buttplug, recordings, and leaderboard sub-pages

- Add /play sidebar layout (mobile nav + desktop sidebar) with SexyBackground
- Move buttplug device control to /play/buttplug with Empty component and scan button
- Move recordings from /me/recordings to /play/recordings
- Move leaderboard to /play/leaderboard; redirect /leaderboard → /play/leaderboard
- Redirect /me/recordings → /play/recordings and /play → /play/buttplug
- Remove recordings entry from /me sidebar nav
- Rename "SexyPlay" → "Play", swap bluetooth icon for rocket, remove subtitle
- Add play.nav i18n keys (play, recordings, leaderboard, back_to_site, back_mobile)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/routes/users/[id]/+page.svelte

@@ -131,7 +131,7 @@
               <span class="icon-[ri--trophy-line] w-6 h-6 text-primary"></span>
               {$_("gamification.stats")}
             </h2>
-            <Button variant="outline" size="sm" href="/leaderboard">
+            <Button variant="outline" size="sm" href="/play/leaderboard">
               <span class="icon-[ri--bar-chart-line] w-4 h-4 mr-2"></span>
               {$_("gamification.leaderboard")}
             </Button>