Added IsBlocked method to Storage interface that checks if an issue is
in the blocked_issues_cache and returns the blocking issue IDs.
The close command now checks for blockers before allowing an issue to
be closed:
- If an issue has open blockers, closing is blocked with an error message
- The --force flag overrides this check
- Works in both daemon mode (RPC) and direct storage mode
- Also handles cross-rig routed IDs
This addresses the bug where agents could close a bead even when it
depends on an open bug/issue.
Closes#962
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>