refactor: move brother_node development artifact to dev/test-nodes subdirectory

Development Artifact Cleanup:
✅ BROTHER_NODE REORGANIZATION: Moved development test node to appropriate location
- dev/test-nodes/brother_node/: Moved from root directory for better organization
- Contains development configuration, test logs, and test chain data
- No impact on production systems - purely development/testing artifact

✅ DEVELOPMENT ARTIFACTS IDENTIFIED:
- Chain ID: aitbc-brother-chain (test/development chain)
- Ports: 8010 (P2P) and 8011 (RPC) - different from production
- Environment: .env file with test configuration
- Logs: rpc.log and node.log from development testing session (March 15, 2026)

✅ ROOT DIRECTORY CLEANUP: Removed development clutter from production directory
- brother_node/ moved to dev/test-nodes/brother_node/
- Root directory now contains only production-ready components
- Development artifacts properly organized in dev/ subdirectory

DIRECTORY STRUCTURE IMPROVEMENT:
📁 dev/test-nodes/: Development and testing node configurations
🏗️ Root Directory: Clean production structure with only essential components
🧪 Development Isolation: Test environments separated from production

BENEFITS:
✅ Clean Production Directory: No development artifacts in root
✅ Better Organization: Development nodes grouped in dev/ subdirectory
✅ Clear Separation: Production vs development environments clearly distinguished
✅ Maintainability: Easier to identify and manage development components

RESULT: Successfully moved brother_node development artifact to dev/test-nodes/ subdirectory, cleaning up the root directory while preserving development testing environment for future use.

dev/env/node_modules/@openzeppelin/contracts/utils/cryptography/MessageHashUtils.sol

@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.3.0) (utils/cryptography/MessageHashUtils.sol)
+
+pragma solidity ^0.8.20;
+
+import {Strings} from "../Strings.sol";
+
+/**
+ * @dev Signature message hash utilities for producing digests to be consumed by {ECDSA} recovery or signing.
+ *
+ * The library provides methods for generating a hash of a message that conforms to the
+ * https://eips.ethereum.org/EIPS/eip-191[ERC-191] and https://eips.ethereum.org/EIPS/eip-712[EIP 712]
+ * specifications.
+ */
+library MessageHashUtils {
+    /**
+     * @dev Returns the keccak256 digest of an ERC-191 signed data with version
+     * `0x45` (`personal_sign` messages).
+     *
+     * The digest is calculated by prefixing a bytes32 `messageHash` with
+     * `"\x19Ethereum Signed Message:\n32"` and hashing the result. It corresponds with the
+     * hash signed when using the https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_sign[`eth_sign`] JSON-RPC method.
+     *
+     * NOTE: The `messageHash` parameter is intended to be the result of hashing a raw message with
+     * keccak256, although any bytes32 value can be safely used because the final digest will
+     * be re-hashed.
+     *
+     * See {ECDSA-recover}.
+     */
+    function toEthSignedMessageHash(bytes32 messageHash) internal pure returns (bytes32 digest) {
+        assembly ("memory-safe") {
+            mstore(0x00, "\x19Ethereum Signed Message:\n32") // 32 is the bytes-length of messageHash
+            mstore(0x1c, messageHash) // 0x1c (28) is the length of the prefix
+            digest := keccak256(0x00, 0x3c) // 0x3c is the length of the prefix (0x1c) + messageHash (0x20)
+        }
+    }
+
+    /**
+     * @dev Returns the keccak256 digest of an ERC-191 signed data with version
+     * `0x45` (`personal_sign` messages).
+     *
+     * The digest is calculated by prefixing an arbitrary `message` with
+     * `"\x19Ethereum Signed Message:\n" + len(message)` and hashing the result. It corresponds with the
+     * hash signed when using the https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_sign[`eth_sign`] JSON-RPC method.
+     *
+     * See {ECDSA-recover}.
+     */
+    function toEthSignedMessageHash(bytes memory message) internal pure returns (bytes32) {
+        return
+            keccak256(bytes.concat("\x19Ethereum Signed Message:\n", bytes(Strings.toString(message.length)), message));
+    }
+
+    /**
+     * @dev Returns the keccak256 digest of an ERC-191 signed data with version
+     * `0x00` (data with intended validator).
+     *
+     * The digest is calculated by prefixing an arbitrary `data` with `"\x19\x00"` and the intended
+     * `validator` address. Then hashing the result.
+     *
+     * See {ECDSA-recover}.
+     */
+    function toDataWithIntendedValidatorHash(address validator, bytes memory data) internal pure returns (bytes32) {
+        return keccak256(abi.encodePacked(hex"19_00", validator, data));
+    }
+
+    /**
+     * @dev Variant of {toDataWithIntendedValidatorHash-address-bytes} optimized for cases where `data` is a bytes32.
+     */
+    function toDataWithIntendedValidatorHash(
+        address validator,
+        bytes32 messageHash
+    ) internal pure returns (bytes32 digest) {
+        assembly ("memory-safe") {
+            mstore(0x00, hex"19_00")
+            mstore(0x02, shl(96, validator))
+            mstore(0x16, messageHash)
+            digest := keccak256(0x00, 0x36)
+        }
+    }
+
+    /**
+     * @dev Returns the keccak256 digest of an EIP-712 typed data (ERC-191 version `0x01`).
+     *
+     * The digest is calculated from a `domainSeparator` and a `structHash`, by prefixing them with
+     * `\x19\x01` and hashing the result. It corresponds to the hash signed by the
+     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`] JSON-RPC method as part of EIP-712.
+     *
+     * See {ECDSA-recover}.
+     */
+    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32 digest) {
+        assembly ("memory-safe") {
+            let ptr := mload(0x40)
+            mstore(ptr, hex"19_01")
+            mstore(add(ptr, 0x02), domainSeparator)
+            mstore(add(ptr, 0x22), structHash)
+            digest := keccak256(ptr, 0x42)
+        }
+    }
+}