Add real-time log monitoring and system stats dashboard

Implements a comprehensive monitoring system for the admin interface:

Backend:
- New monitoring package with Redis ring buffer for log storage
- Zerolog MultiWriter to capture logs to Redis
- System stats collection (CPU, memory, disk, goroutines, GC)
- HTTP metrics middleware (request counts, latency, error rates)
- Asynq queue stats for worker process
- WebSocket endpoint for real-time log streaming
- Admin auth middleware now accepts token in query params (for WebSocket)

Frontend:
- New monitoring page with tabs (Overview, Logs, API Stats, Worker Stats)
- Real-time log viewer with level filtering and search
- System stats cards showing CPU, memory, goroutines, uptime
- HTTP endpoint statistics table
- Asynq queue depth visualization
- Enable/disable monitoring toggle in settings

Memory safeguards:
- Max 200 unique endpoints tracked
- Hourly stats reset to prevent unbounded growth
- Max 1000 log entries in ring buffer
- Max 1000 latency samples for P95 calculation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

cmd/worker/main.go

@@ -8,10 +8,12 @@ import (
 	"syscall"
 
 	"github.com/hibiken/asynq"
+	"github.com/redis/go-redis/v9"
 	"github.com/rs/zerolog/log"
 
 	"github.com/treytartt/casera-api/internal/config"
 	"github.com/treytartt/casera-api/internal/database"
+	"github.com/treytartt/casera-api/internal/monitoring"
 	"github.com/treytartt/casera-api/internal/push"
 	"github.com/treytartt/casera-api/internal/repositories"
 	"github.com/treytartt/casera-api/internal/services"
@@ -70,6 +72,43 @@ func main() {
 		log.Fatal().Err(err).Msg("Failed to parse Redis URL")
 	}
 
+	// Initialize monitoring service (if Redis is available)
+	var monitoringService *monitoring.Service
+	redisClientOpt, ok := redisOpt.(asynq.RedisClientOpt)
+	if ok {
+		redisClient := redis.NewClient(&redis.Options{
+			Addr:     redisClientOpt.Addr,
+			Password: redisClientOpt.Password,
+			DB:       redisClientOpt.DB,
+		})
+
+		// Verify Redis connection
+		if err := redisClient.Ping(context.Background()).Err(); err != nil {
+			log.Warn().Err(err).Msg("Failed to connect to Redis for monitoring - monitoring disabled")
+		} else {
+			monitoringService = monitoring.NewService(monitoring.Config{
+				Process:     "worker",
+				RedisClient: redisClient,
+				DB:          db, // Pass database for enable_monitoring setting sync
+			})
+
+			// Reinitialize logger with monitoring writer
+			utils.InitLoggerWithWriter(cfg.Server.Debug, monitoringService.LogWriter())
+
+			// Create Asynq inspector for queue statistics
+			inspector := asynq.NewInspector(redisOpt)
+			monitoringService.SetAsynqInspector(inspector)
+
+			// Start stats collection
+			monitoringService.Start()
+			defer monitoringService.Stop()
+
+			log.Info().
+				Bool("log_capture_enabled", monitoringService.IsEnabled()).
+				Msg("Monitoring service initialized")
+		}
+	}
+
 	// Create Asynq server
 	srv := asynq.NewServer(
 		redisOpt,