store last block commitment timestamp in router storage

ethexe/contracts/src/IRouter.sol

@@ -5,14 +5,14 @@ pragma solidity ^0.8.26;
 interface IRouter {
     /* Storage related structures */
 
-    // TODO (breathx): should we store here something about commitment and timestamp?
     /// @custom:storage-location erc7201:router.storage.Router
     struct Storage {
         bytes32 genesisBlockHash;
         address mirror;
         address mirrorProxy;
         address wrappedVara;
         bytes32 lastBlockCommitmentHash;
+        uint48 lastBlockCommitmentTimestamp;
         uint256 signingThresholdPercentage;
         uint64 baseWeight;
         uint128 valuePerWeight;
@@ -167,6 +167,8 @@ interface IRouter {
 
     function lastBlockCommitmentHash() external view returns (bytes32);
 
+    function lastBlockCommitmentTimestamp() external view returns (uint48);
+
     function wrappedVara() external view returns (address);
 
     function mirrorProxy() external view returns (address);

ethexe/contracts/src/Router.sol

@@ -89,6 +89,11 @@ contract Router is IRouter, OwnableUpgradeable, ReentrancyGuardTransient {
         return router.lastBlockCommitmentHash;
     }
 
+    function lastBlockCommitmentTimestamp() public view returns (uint48) {
+        Storage storage router = _getStorage();
+        return router.lastBlockCommitmentTimestamp;
+    }
+
     function wrappedVara() public view returns (address) {
         Storage storage router = _getStorage();
         return router.wrappedVara;
@@ -355,6 +360,7 @@ contract Router is IRouter, OwnableUpgradeable, ReentrancyGuardTransient {
          * @dev SECURITY: this settlement should be performed before any other calls to avoid reentrancy.
          */
         router.lastBlockCommitmentHash = blockCommitment.blockHash;
+        router.lastBlockCommitmentTimestamp = blockCommitment.blockTimestamp;
 
         bytes memory transitionsHashes;