retry_count column and filter existed but counter was never
incremented. Stuck commands always had retry_count=0 and
always passed the WHERE retry_count < 5 filter, making
the cap ineffective.
Fix: Added RedeliverStuckCommandTx that sets
retry_count = retry_count + 1 on stuck->sent re-delivery.
GetCommands handler now uses MarkCommandSentTx for new
commands (retry_count stays 0) and RedeliverStuckCommandTx
for stuck re-delivery (retry_count increments).
All 77 tests pass. DEV-029 resolved.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>