Complete bias source lifecycle commands

Completed. Added meeting-locked commands for pending proposal withdrawal and hard deletion, including overlay inverses, delayed-batch re-evaluation, declaration/invitation cleanup, and cascade validation. Direct declaration overlays convert atomically to formal pending proposals while retaining candidate intent. Identity-affecting proposer/type edits and registered-bias merges are rejected. Existing immediate/delayed, reset-one-decision, and unavailable-candidate behavior remains covered.