verify: B-2 data integrity verification — fixes verified with 1 follow-up

All B-2 concurrency fixes verified:
- Registration transaction: atomic, no orphaned agents
- SELECT FOR UPDATE SKIP LOCKED: prevents duplicate delivery
- Token renewal: atomic validate + update
- GetCommands: rate limited with agent_checkin key
- Jitter: capped at min(pollingInterval/2, 30s)
- Exponential backoff: base=10s, cap=5min, reset on success

Finding: DEV-029 — retry_count column exists but never incremented.
Filter is in place but ineffective. Targeted fix needed.

77 tests pass. No regressions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/Deviations_Report.md

@@ -284,3 +284,13 @@ This document records deviations from the implementation spec.
 **Issue:** `018_create_scanner_config_table.sql` had wrong file suffix (.sql not .up.sql) AND shared number 018 with `018_create_metrics_and_docker_tables.up.sql`.
 
 **Decision:** Renumbered to 027. The scanner_config table has never been created by the runner (it was skipped due to wrong suffix), so existing databases don't have it. Number 027 is after all existing migrations, ensuring it runs last in the sequence.
+
+---
+
+## DEV-029: retry_count column exists but is never incremented (B-2 verification)
+
+**Issue found during B-2 verification:** Migration 029 adds `retry_count` to `agent_commands` and `GetStuckCommands` filters `retry_count < 5`. However, `MarkCommandSentTx` does not increment `retry_count` when re-delivering stuck commands. The column exists and the filter is in the query, but the counter stays at 0 forever, making the filter ineffective.
+
+**Impact:** LOW — stuck commands are not capped at 5 retries as intended. They continue to be re-delivered indefinitely (pre-fix behavior). The fix is structurally correct (column, index, filter all in place) but the increment step was missed.
+
+**Action required:** Add `retry_count = retry_count + 1` to the UPDATE in `MarkCommandSentTx` or add a separate function for stuck command re-delivery that increments the counter. This is a targeted one-line fix for the next round.