Clarify ArgoCD status and update MySQL→MariaDB

- ArgoCD: Installed but not configured yet (Fase 4)
- All MySQL references updated to MariaDB 11.4 LTS
- Current CI/CD: Gitea Actions (active)
- Future GitOps: ArgoCD (pending configuration)

Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>

README.md

@@ -64,8 +64,8 @@ Tarea → Agente → Código → PR → Preview Deploy → Aprobación → Stagi
 - ✅ MariaDB 11.4 LTS
 - ✅ Redis 7
 - ✅ Gitea 1.25.3 + Container Registry
-- ✅ ArgoCD
-- ✅ Gitea Actions Runner (CI/CD)
+- ✅ ArgoCD (instalado, pendiente configuración)
+- ✅ Gitea Actions Runner (CI/CD activo)
 
 ### Backend Inicial
 - ✅ Estructura del proyecto