fix: also add prettier as direct devDependency

pnpm strict mode does not expose transitive dependency binaries.
Adding prettier@^2.8.8 alongside eslint@^8.57.0 so that
pnpm run format:check works in CI without 'prettier: not found'.

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

package.json

@@ -49,6 +49,7 @@
     "@vitest/coverage-v8": "^3.2.4",
     "eslint": "^8.57.0",
     "jsdom": "^24.0.0",
+    "prettier": "^2.8.8",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-router-dom": "^5.3.0",

pnpm-lock.yaml

@@ -46,6 +46,9 @@ importers:
       jsdom:
         specifier: ^24.0.0
         version: 24.1.3
+      prettier:
+        specifier: ^2.8.8
+        version: 2.8.8
       react:
         specifier: ^18.3.1
         version: 18.3.1