feat: constitutional committee endpoints
Adds three endpoints for surfacing constitutional committee state and votes:
- GET /governance/committee — current committee snapshot with members,
quorum, members count, and source NewCommittee gov action (genesis
committee returns proposal fields as null and `is_genesis: true`).
- GET /governance/committee/votes — paged list of all CC votes ever cast.
- GET /governance/committee/:cc_id/votes — paged list of votes filtered
by CIP-129 hot (cc_hot1...) or cold (cc_cold1...) credential.
Cold queries aggregate across every hot key the cold has authorized.
Per-vote shape includes the voting anchor (metadata_url / metadata_hash),
governance_type, block height/time, and the voter's CIP-129 hot id.
Depends on a forthcoming @blockfrost/openapi release that adds the
matching path + schema definitions.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>