Add prettier formatting and CI validation checks

- Add prettier with consistent formatting config
- Add format and format:check npm scripts
- Add prettier pre-commit hook
- Add validation and formatting checks to CI workflow
- Reformat all TypeScript and JSON files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -33,4 +33,10 @@ jobs:
         run: npm ci
 
       - name: Build
-        run: npm run build
+        run: npm run build
+
+      - name: Validate config
+        run: npm run validate
+
+      - name: Check formatting
+        run: npm run format:check