Add mainnet checkpoint stack: ISO attestation, participant Etherscan surface, and services.

Ship AddressActivityRegistry V1/V2, ISO20022IntakeGateway, Chain138ParticipantSurface,
checkpoint hub contracts, checkpoint-core package, aggregator/indexer/sdk services,
relay profile guards, M00 diamond bridge facet, and OMNL compliance contracts.

Co-authored-by: Cursor <cursoragent@cursor.com>

script/mainnet-checkpoint/UpgradeChain138MainnetCheckpointV3.s.sol

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import {Script, console} from "forge-std/Script.sol";
+import {Chain138MainnetCheckpoint} from "../../contracts/mainnet-checkpoint/Chain138MainnetCheckpoint.sol";
+
+/// @notice UUPS upgrade: extension hook wiring (validator sigs vs leaf payload). IMPLEMENTATION_VERSION 3.
+contract UpgradeChain138MainnetCheckpointV3 is Script {
+    function run() external {
+        address proxy = vm.envAddress("CHAIN138_MAINNET_CHECKPOINT_PROXY");
+        uint256 pk = vm.envUint("PRIVATE_KEY");
+
+        vm.startBroadcast(pk);
+        Chain138MainnetCheckpoint newImpl = new Chain138MainnetCheckpoint();
+        console.log("New impl:", address(newImpl));
+        Chain138MainnetCheckpoint(proxy).upgradeToAndCall(address(newImpl), "");
+        console.log("Upgraded proxy:", proxy);
+        require(Chain138MainnetCheckpoint(proxy).IMPLEMENTATION_VERSION() == 3, "version");
+        vm.stopBroadcast();
+    }
+}