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>

internal/middleware/admin_auth.go

@@ -32,21 +32,27 @@ type AdminClaims struct {
 // AdminAuthMiddleware creates a middleware that validates admin JWT tokens
 func AdminAuthMiddleware(cfg *config.Config, adminRepo *repositories.AdminRepository) gin.HandlerFunc {
 	return func(c *gin.Context) {
+		var tokenString string
+
 		// Get token from Authorization header
 		authHeader := c.GetHeader("Authorization")
-		if authHeader == "" {
-			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Authorization header required"})
-			return
+		if authHeader != "" {
+			// Check Bearer prefix
+			parts := strings.SplitN(authHeader, " ", 2)
+			if len(parts) == 2 && strings.ToLower(parts[0]) == "bearer" {
+				tokenString = parts[1]
+			}
 		}
 
-		// Check Bearer prefix
-		parts := strings.SplitN(authHeader, " ", 2)
-		if len(parts) != 2 || strings.ToLower(parts[0]) != "bearer" {
-			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Invalid authorization header format"})
-			return
+		// If no header token, check query parameter (for WebSocket connections)
+		if tokenString == "" {
+			tokenString = c.Query("token")
 		}
 
-		tokenString := parts[1]
+		if tokenString == "" {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "Authorization required"})
+			return
+		}
 
 		// Parse and validate token
 		claims := &AdminClaims{}