fix: resolve dashboard 401 and 500 errors

Restricted AuthMiddleware to /v1 group to prevent dashboard session interference. Robustified analytics SQL queries with COALESCE to handle empty datasets.

internal/server/server.go

@@ -74,8 +74,6 @@ func NewServer(cfg *config.Config, database *db.DB) *Server {
 }
 
 func (s *Server) setupRoutes() {
-	s.router.Use(middleware.AuthMiddleware(s.database))
-
 	// Static files
 	s.router.StaticFile("/", "./static/index.html")
 	s.router.StaticFile("/favicon.ico", "./static/favicon.ico")
@@ -86,7 +84,7 @@ func (s *Server) setupRoutes() {
 	// WebSocket
 	s.router.GET("/ws", s.handleWebSocket)
 
-	// API V1 (External LLM Access)
+	// API V1 (External LLM Access) - Secured with AuthMiddleware
 	v1 := s.router.Group("/v1")
 	v1.Use(middleware.AuthMiddleware(s.database))
 	{