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/access/Ownable.sol

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)
+
+pragma solidity ^0.8.20;
+
+import {Context} from "../utils/Context.sol";
+
+/**
+ * @dev Contract module which provides a basic access control mechanism, where
+ * there is an account (an owner) that can be granted exclusive access to
+ * specific functions.
+ *
+ * The initial owner is set to the address provided by the deployer. This can
+ * later be changed with {transferOwnership}.
+ *
+ * This module is used through inheritance. It will make available the modifier
+ * `onlyOwner`, which can be applied to your functions to restrict their use to
+ * the owner.
+ */
+abstract contract Ownable is Context {
+    address private _owner;
+
+    /**
+     * @dev The caller account is not authorized to perform an operation.
+     */
+    error OwnableUnauthorizedAccount(address account);
+
+    /**
+     * @dev The owner is not a valid owner account. (eg. `address(0)`)
+     */
+    error OwnableInvalidOwner(address owner);
+
+    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
+
+    /**
+     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
+     */
+    constructor(address initialOwner) {
+        if (initialOwner == address(0)) {
+            revert OwnableInvalidOwner(address(0));
+        }
+        _transferOwnership(initialOwner);
+    }
+
+    /**
+     * @dev Throws if called by any account other than the owner.
+     */
+    modifier onlyOwner() {
+        _checkOwner();
+        _;
+    }
+
+    /**
+     * @dev Returns the address of the current owner.
+     */
+    function owner() public view virtual returns (address) {
+        return _owner;
+    }
+
+    /**
+     * @dev Throws if the sender is not the owner.
+     */
+    function _checkOwner() internal view virtual {
+        if (owner() != _msgSender()) {
+            revert OwnableUnauthorizedAccount(_msgSender());
+        }
+    }
+
+    /**
+     * @dev Leaves the contract without owner. It will not be possible to call
+     * `onlyOwner` functions. Can only be called by the current owner.
+     *
+     * NOTE: Renouncing ownership will leave the contract without an owner,
+     * thereby disabling any functionality that is only available to the owner.
+     */
+    function renounceOwnership() public virtual onlyOwner {
+        _transferOwnership(address(0));
+    }
+
+    /**
+     * @dev Transfers ownership of the contract to a new account (`newOwner`).
+     * Can only be called by the current owner.
+     */
+    function transferOwnership(address newOwner) public virtual onlyOwner {
+        if (newOwner == address(0)) {
+            revert OwnableInvalidOwner(address(0));
+        }
+        _transferOwnership(newOwner);
+    }
+
+    /**
+     * @dev Transfers ownership of the contract to a new account (`newOwner`).
+     * Internal function without access restriction.
+     */
+    function _transferOwnership(address newOwner) internal virtual {
+        address oldOwner = _owner;
+        _owner = newOwner;
+        emit OwnershipTransferred(oldOwner, newOwner);
+    }
+}