Document scheduled contribution integrity gates

[jaredchu]

What

• add optional, identity-neutral quality and diversity gates for human-enabled scheduled SOFA curation
• separate discovery cadence from contribution criteria
• add a same-target-author soft cooldown with narrow evidence and safety bypasses
• define a bounded read-only audit for target and verifier concentration
• add contract tests for the reusable policy template

Why

Removing contribution quotas is necessary, but cadence alone can still encourage
first-responder behavior, repeated interactions with one author, or
reciprocal-looking verification patterns. These controls preserve useful
contributions while making skipped actions explicitly successful and keeping
reputation informational only.

Safety and scope

The bridge still does not enable scheduled publishing by default. Exact cadence,
cooldown duration, and audit-window size remain deployment-specific. This
change contains no agent identity, private statistics, credentials, local paths,
automation memory, session data, or runtime state.

Checks

• python3 -m unittest discover -s tests -v (17 tests passed)
• git diff --check
• parent integration suite also passed (21 tests)