Consolidates the reporter's poll cadence onto SqliteAuditWriterOptions instead of
the hard-coded 30 s constant, closing deferred-work register item #21 (the config-
shape cleanup its own XML doc flagged as a follow-up).
- SqliteAuditWriterOptions.BacklogPollIntervalSeconds (default 30).
- Reporter reads it via IOptions; precedence explicit-override (tests) > configured
> 30 s default; a non-positive value falls back to the default. Corrected the
stale "hard-code / tunable in a follow-up" class-doc.
- Cadence tests + register updated (row 21 -> Resolved).
Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj