Add monitoring service and database schema

- Implement monitoring service with heartbeat, lease tasks, resume tasks, and task result handling.
- Create monitoring time utilities for business date calculations.
- Add unit tests for date window resolution and business day handling.
- Define database schema for monitoring-related tables including quotas, daily reports, and task management.
- Establish migration scripts for creating and dropping monitoring tables.

server/internal/tenant/transport/router_test.go

@@ -29,6 +29,7 @@ func TestProtectedRoutes_RequireAuth(t *testing.T) {
 		{http.MethodGet, "/api/tenant/templates"},
 		{http.MethodGet, "/api/tenant/articles"},
 		{http.MethodGet, "/api/tenant/brands"},
+		{http.MethodGet, "/api/tenant/monitoring/brands/:brand_id/questions/:question_id/detail"},
 		{http.MethodPost, "/api/tenant/brands"},
 	}
 
@@ -50,6 +51,11 @@ func TestPublicRoutes_NoAuth(t *testing.T) {
 	}{
 		{http.MethodPost, "/api/auth/login"},
 		{http.MethodPost, "/api/auth/refresh"},
+		{http.MethodPost, "/api/plugin/monitoring/heartbeat"},
+		{http.MethodPost, "/api/plugin/monitoring/tasks/lease"},
+		{http.MethodPost, "/api/plugin/monitoring/tasks/resume"},
+		{http.MethodPost, "/api/plugin/monitoring/tasks/:id/result"},
+		{http.MethodPost, "/api/plugin/monitoring/tasks/:id/skip"},
 		{http.MethodGet, "/api/health/live"},
 		{http.MethodGet, "/api/health/ready"},
 	}