fix(cli): skip initial commit when git user.name or user.email is not set

[gonzoblasco]

What

Fixes #231

The CLI was crashing when trying to run git commit --amend without git user.name or user.email configured. This happened because isGitInitialized only checks for the existence of .git/, not whether git identity is properly set up.

Why

Create Next App may succeed at initializing git (creating .git/) but the subsequent git commit --amend from CNS fails if the user hasn't configured their git identity. This is common in CI/CD environments and fresh setups.

create-next-app handles this gracefully, so CNS should too.

How

• Added hasGitUserConfig helper that checks both user.name and user.email via git config
• If either is missing, the initial commit step is skipped with a warning message instructing the user how to configure them
• The check uses git config user.name (without --global) so it works with both global and local config

Testing

• tsc --noEmit passes
• Unit tests pass (pnpm test:cli)
• The fix follows the same pattern as the existing isGitInitialized check

[vercel]

@gonzoblasco is attempting to deploy a commit to the 9ty Team on Vercel.

A member of the Team first needs to authorize it.