1ac4a0f66d
- ActivityLogEntry dataclass + ActivityCategory/ActivitySeverity + ActivityLogFilters - additive idempotent migration 002_add_activity_log (indexed activity_log table, seq keyset tiebreaker) - ActivityLogRepository (record/query/count/prune/clear/iter_export), keyset pagination, parameterized SQL - 102 unit + adversarial tests (SQL-injection, pagination, prune, codec, migration idempotency)