- alert_entity_scope: add is_attributable_period / guard_alert_period (R5) and entity_alert_guard (R1, any write path)
- alert_rules.run_all_alert_checks: skip non-YYYY-MM period alert rows (R5)
- bot_bridge / bot_bridge_v2: R1 demo-entity guard + R5 period guard on write paths
- tests: new R5 suite (10 cases)
Not pushed / not deployed (release gate held by 任总).