Add gt doctor checks for ephemeral beads repos:
- ephemeral-exists: Verify .beads-ephemeral/ exists for each rig (fixable)
- ephemeral-git: Verify it's a valid git repo (fixable)
- ephemeral-orphans: Detect molecules >24h old (needs manual review)
- ephemeral-size: Warn if repo >100MB
- ephemeral-stale: Detect molecules with no activity in last hour
Implements gt-3x0z.3.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>