feat: add governance voting messages and fields to the Cardano transaction proto definition.

proto/utxorpc/v1beta/cardano/cardano.proto

@@ -108,6 +108,7 @@ message Tx {
   AuxData auxiliary = 12; // Auxiliary data not directly tied to the validation process
   bytes hash = 13; // Hash of the transaction that serves as main identifier
   repeated GovernanceActionProposal proposals = 14; // List of governance actions proposed
+  repeated VoterVotes votes = 15; // List of voters and their corresponding votes cast in this transaction
 }
 
 // Define a governance action proposal
@@ -136,6 +137,33 @@ message GovernanceActionId {
   uint32 governance_action_index = 2;
 }
 
+// Valid vote choices for a governance action (CIP-1694).
+// On-chain CBOR mapping: No=0, Yes=1, Abstain=2.
+enum Vote {
+  VOTE_UNSPECIFIED = 0;
+  VOTE_NO = 1;
+  VOTE_YES = 2;
+  VOTE_ABSTAIN = 3;
+}
+
+// A single cast vote on a governance action.
+message VotingProcedure {
+  GovernanceActionId gov_action_id = 1; // ID of the governance action being voted on.
+  Vote vote = 2;                        // The vote cast.
+  optional Anchor anchor = 3;           // Optional anchor for voter rationale.
+}
+
+// Groups a voter with all votes they cast in the transaction.
+// SPOs can only identify via pool key hash; DReps and CC members may use key or script hash.
+message VoterVotes {
+  oneof voter {
+    StakeCredential constitutional_committee = 1; // Constitutional Committee member.
+    StakeCredential drep = 2;                     // Delegated Representative.
+    bytes spo = 3;                                // Stake Pool Operator (pool key hash).
+  }
+  repeated VotingProcedure votes = 4; // Votes cast by this voter.
+}
+
 message ParameterChangeAction {
   GovernanceActionId gov_action_id = 1;
   PParams protocol_param_update = 2; // The updates proposed