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/api.ts

@@ -14,6 +14,7 @@ import type {
   MediaFilter,
   TranscodeSettings,
   TranscodeStats,
+  ActivityEvent,
 } from "@/lib/types";
 
 const API_BASE =
@@ -175,6 +176,11 @@ export const api = {
       request<void>("/files/transcode-cache", { method: "DELETE", token }),
   },
 
+  admin: {
+    activity: (token: string) =>
+      request<ActivityEvent[]>("/admin/activity", { token }),
+  },
+
   schedule: {
     generate: (channelId: string, token: string) =>
       request<ScheduleResponse>(`/channels/${channelId}/schedule`, {