Fix frontend TypeScript build errors

- Inline tsconfig.base.json settings into frontend/tsconfig.json (same
  Docker context issue as backend — only frontend/ is copied)
- Upgrade @types/react and @types/react-dom to ^19.0.0 to satisfy
  antd 5.20.x which references React.ActionDispatch (React 19 type);
  React 18 runtime is unchanged

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/package.json

@@ -21,8 +21,8 @@
     "zustand": "^4.5.5"
   },
   "devDependencies": {
-    "@types/react": "^18.3.5",
-    "@types/react-dom": "^18.3.0",
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
     "@vitejs/plugin-react": "^4.3.1",
     "typescript": "^5.5.4",
     "vite": "^5.4.3"