feat: enable React Compiler on Next 16

Auto-memoization via babel-plugin-react-compiler (stable in Next 16),
compiled through Turbopack's built-in babel. Build and test suite pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

package.json

@@ -67,6 +67,7 @@
     "@testing-library/react": "^16.3.2",
     "@testing-library/user-event": "^14.6.1",
     "@vitejs/plugin-react": "^4.7.0",
+    "babel-plugin-react-compiler": "^1.0.0",
     "cross-env": "^10.1.0",
     "eslint": "^9.39.4",
     "eslint-config-next": "^16.2.10",