Problem: Version check middleware blocked old agents from checking in to receive
update commands, creating a deadlock where agents couldn't upgrade because they
were blocked from checking in.
Solution: Modified MachineBindingMiddleware to allow old agents checking in for
commands to proceed IF they have a pending update_agent command. This allows
agents to receive the update command even when below minimum version.
Changes:
- Added grace period logic in middleware for command endpoints
- Check if agent has pending update command before blocking
- If update pending, allow check-in and log it
- Added HasPendingUpdateCommand() to AgentQueries for checking pending updates
- Also added same method to CommandQueries for completeness
This prevents the version tracking deadlock while maintaining security for
agents without pending updates.
NOTE: Need to test that old agents can actually receive and execute update
commands when allowed through this path.
