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/lib/types.ts

@@ -1,5 +1,20 @@
 // API response and request types matching the backend DTOs
 
+export interface ActivityEvent {
+  id: string;
+  timestamp: string;
+  event_type: string;
+  detail: string;
+  channel_id?: string;
+}
+
+export interface LogLine {
+  level: string;
+  target: string;
+  message: string;
+  timestamp: string;
+}
+
 export type ContentType = "movie" | "episode" | "short";
 
 export type AccessMode = "public" | "password_protected" | "account_required" | "owner_only";