[Deep-Sixed]

Fixes the two remaining governance findings from the review of main after #21/#32.

1. Protected ref rules now compose with force/delete rules

A protected ref previously took precedence over force_update and ref_delete, so stricter per-operation policies for force pushes and deletions were skipped on protected refs.

Now ref-level operations are additive:

• protected ordinary update -> protected_ref_update
• protected force update -> protected_ref_update + force_update
• protected deletion -> protected_ref_update + ref_delete

The existing all-or-nothing multi-approval path handles the composed operations.

2. Quorum execution never counts the executor's own vote

Fixed-threshold behavior is unchanged: an approver cannot consume its own approval.

Under quorum policy, if the consumer also voted yes, that consumer is removed from both:

• the eligible yes-vote count, and
• the quorum denominator.

Consumption succeeds only if the other currently eligible approvers still satisfy 2/3 + 1 (and the fixed threshold floor). This prevents small quorums from becoming impossible to execute without allowing self-authorization.

Migration 011_quorum_consumer_separation.sql:

• adds the effective quorum bit to approval_effective_policy
• adds approval_eligible_agents
• recreates the database consumption trigger with the same rule as the Python gate

Regression coverage

• protected force update requires both protected-ref and force-update operations
• protected deletion requires both protected-ref and ref-delete operations
• per-operation thresholds remain distinct when the rules compose
• a 3-of-3 quorum voter can execute only because the other 2 independently form the consumer-specific quorum
• the SQLite trigger is exercised by that consumption path
• migration upgrade lists and contract views are updated
• README and agent guide document the behavior