Add pinned status for beads that should stay open indefinitely: - Add StatusPinned constant and update IsValid() - Add PinnedIssues count to Statistics struct - Protect pinned issues from bd close (requires --force) - Show pinned count in bd stats output 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>