feat: add TypeScript support and testing setup

- Introduced TypeScript configuration files (tsconfig.json, tsconfig.build.json)
- Added Vitest configuration for testing (vitest.config.ts)
- Created initial test file (index.test.ts) with a basic test case
- Updated package.json scripts for TypeScript build and testing
- Refactored ESLint configuration to support TypeScript
- Implemented main action logic in TypeScript (index.ts)

Author: amondnet

.prettierignore

@@ -0,0 +1,7 @@
+dist/
+node_modules/
+example/
+*.d.ts
+*.d.ts.map
+*.js.map
+coverage/

test/index.test.ts

@@ -4,4 +4,4 @@ describe('vercel-action', () => {
   it('should pass basic test', () => {
     expect(true).toBe(true);
   });
-});
+});