feat: add server-sent events for logging and activity tracking

- Implemented a custom tracing layer (`AppLogLayer`) to capture log events and broadcast them to SSE clients.
- Created admin routes for streaming server logs and listing recent activity logs.
- Added an activity log repository interface and SQLite implementation for persisting activity events.
- Integrated activity logging into user authentication and channel CRUD operations.
- Developed frontend components for displaying server logs and activity logs in the admin panel.
- Enhanced the video player with a stats overlay for monitoring streaming metrics.

k-tv-frontend/app/(main)/layout.tsx

@@ -6,6 +6,7 @@ const NAV_LINKS = [
   { href: "/tv", label: "TV" },
   { href: "/guide", label: "Guide" },
   { href: "/dashboard", label: "Dashboard" },
+  { href: "/admin", label: "Admin" },
   { href: "/docs", label: "Docs" },
 ];