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>

.prettierrc

@@ -0,0 +1,7 @@
+{
+  "semi": true,
+  "singleQuote": true,
+  "trailingComma": "es5",
+  "printWidth": 100,
+  "tabWidth": 2
+}