Migrate risk_control audit logs to internal/db/batchwriter and add
openflare/chwriter with per-table async flush for observability
timeseries and node access logs.
Replace single-row ClickHouse inserts and pre-insert SELECT count()
dedup with repository BatchInsert* APIs, in-process TTL dedup for
metric/report snapshots, and bootstrap initialization on API startup.
ryan
9491b2a744