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-backend/api/src/main.rs

@@ -2,27 +2,30 @@
 //!
 //! Configures and starts the HTTP server with JWT-based authentication.
 
+use std::collections::VecDeque;
 use std::net::SocketAddr;
+use std::sync::{Arc, Mutex};
 use std::time::Duration as StdDuration;
 
 use axum::Router;
 use axum::http::{HeaderName, HeaderValue};
-use std::sync::Arc;
+use tokio::sync::broadcast;
 use tower_http::cors::{AllowHeaders, AllowMethods, AllowOrigin, CorsLayer};
+use tracing::info;
+use tracing_subscriber::{EnvFilter, fmt, layer::SubscriberExt, util::SubscriberInitExt};
 
 use domain::{ChannelService, IMediaProvider, IProviderRegistry, ProviderCapabilities, ScheduleEngineService, StreamingProtocol, UserService};
-use infra::factory::{build_channel_repository, build_schedule_repository, build_user_repository};
+use infra::factory::{build_activity_log_repository, build_channel_repository, build_schedule_repository, build_user_repository};
 use infra::run_migrations;
 use k_core::http::server::{ServerConfig, apply_standard_middleware};
-use k_core::logging;
 use tokio::net::TcpListener;
-use tracing::info;
 
 mod config;
 mod dto;
 mod error;
 mod events;
 mod extractors;
+mod log_layer;
 mod poller;
 mod routes;
 mod scheduler;
@@ -34,7 +37,16 @@ use crate::state::AppState;
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
-    logging::init("api");
+    // Set up broadcast channel + ring buffer for SSE log streaming.
+    let (log_tx, _) = broadcast::channel::<log_layer::LogLine>(512);
+    let log_history = Arc::new(Mutex::new(VecDeque::<log_layer::LogLine>::new()));
+
+    // Initialize tracing with our custom layer in addition to the fmt layer.
+    tracing_subscriber::registry()
+        .with(EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info")))
+        .with(fmt::layer())
+        .with(log_layer::AppLogLayer::new(log_tx.clone(), Arc::clone(&log_history)))
+        .init();
 
     let config = Config::from_env();
 
@@ -71,6 +83,7 @@ async fn main() -> anyhow::Result<()> {
     let user_repo = build_user_repository(&db_pool).await?;
     let channel_repo = build_channel_repository(&db_pool).await?;
     let schedule_repo = build_schedule_repository(&db_pool).await?;
+    let activity_log_repo = build_activity_log_repository(&db_pool).await?;
 
     let user_service = UserService::new(user_repo);
     let channel_service = ChannelService::new(channel_repo.clone());
@@ -177,6 +190,9 @@ async fn main() -> anyhow::Result<()> {
         registry,
         config.clone(),
         event_tx.clone(),
+        log_tx,
+        log_history,
+        activity_log_repo,
     )
     .await?;