feat: versionamento visível (rodapé + /api/version + carimbo no build)

- backend: endpoint GET /api/version + linha [VERSION] no boot (le APP_VERSION/GIT_COMMIT/BUILD_TIME/APP_ENV)
- frontend: buildInfo.ts le import.meta.env.VITE_* ; versão no rodapé do Sidebar
- Dockerfiles (front+back): ARG/ENV do carimbo de versão
- docker-compose.yml: build args (APP_VERSION/GIT_COMMIT/BUILD_TIME/APP_ENV) com defaults
- bump V1.0.12 -> V1.0.13

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/components/Sidebar.tsx

@@ -7,6 +7,7 @@ import {
 import { ToothIcon } from './ToothIcon.tsx';
 import { HybridBackend } from '../services/backend.ts';
 import { getActivePlugins } from '../views/plugins/pluginRegistry.ts';
+import { BUILD_INFO } from '../buildInfo.ts';
 
 interface SidebarProps {
   activeTab: string;
@@ -283,6 +284,15 @@ export const Sidebar: React.FC<SidebarProps> = ({ activeTab, setActiveTab }) =>
           <LogOut size={16} />
           SAIR DO SISTEMA
         </button>
+
+        <div
+          className="px-4 pt-1 text-[8px] leading-tight text-gray-300 font-mono select-text"
+          title={`Build: ${BUILD_INFO.build || 'n/a'}`}
+        >
+          <span className="font-bold text-gray-400">{BUILD_INFO.version}</span>
+          {' · '}{BUILD_INFO.commit}
+          {' · '}<span className={BUILD_INFO.environment === 'PRODUÇÃO' || BUILD_INFO.environment === 'PROD' ? 'text-emerald-400' : 'text-amber-400'}>{BUILD_INFO.environment}</span>
+        </div>
       </div>
     </div>
   );