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>

package.json

@@ -5,7 +5,9 @@
   "main": "src/index.ts",
   "scripts": {
     "build": "tsc",
-    "validate": "npx ts-node scripts/validate-config.ts"
+    "validate": "npx ts-node scripts/validate-config.ts",
+    "format": "prettier --write .",
+    "format:check": "prettier --check ."
   },
   "license": "MIT",
   "dependencies": {
@@ -15,6 +17,7 @@
   },
   "devDependencies": {
     "@types/node": "^22.18.6",
+    "prettier": "^3.7.2",
     "typescript": "^5.9.2"
   }
 }