Add Prettier for TypeScript formatting

- Install prettier
- Configure .prettierrc.json and .prettierignore
- Add npm scripts: format, format:check
- Add Makefile target: format-frontend
- Format all frontend files

frontend/e2e/helpers/auth.ts

@@ -37,4 +37,3 @@ export async function loginUser(page: Page, email: string, password: string) {
   await page.click('button[type="submit"]');
   await page.waitForURL((url) => !url.pathname.includes("/login"), { timeout: 10000 });
 }
-

frontend/e2e/helpers/date.ts

@@ -20,4 +20,3 @@ export function getTomorrowDateStr(): string {
   tomorrow.setDate(tomorrow.getDate() + 1);
   return formatDateLocal(tomorrow);
 }
-