fix(picker): an Added non-git directory shows a red 'git could not read it' status #87

Part of #61. Found while recording the demo (#74 / PR #86).

What happens

After cdd add ~/Work/notes, where notes is not a git repo, the Picker row shows the red ! "unknown" marker. The preview says status ! git could not read it.

Expected

An Added directory without .git is a valid Project (ADR 0002), so it shouldn't look broken. Show a neutral state instead: no status marker, or a muted not a git repo in the preview, with branch and sync omitted. Keep the red ! for real git failures inside a repository.

Acceptance

• Neither the row nor the preview of an Added non-git directory uses the error/unknown style.
• The legend still makes sense, and the "unknown" entry still applies to real failures.
• View tests cover a non-git row and its preview.