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/ReentrancyGuardTransient.sol

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.3.0) (utils/ReentrancyGuardTransient.sol)
+
+pragma solidity ^0.8.24;
+
+import {TransientSlot} from "./TransientSlot.sol";
+
+/**
+ * @dev Variant of {ReentrancyGuard} that uses transient storage.
+ *
+ * NOTE: This variant only works on networks where EIP-1153 is available.
+ *
+ * _Available since v5.1._
+ */
+abstract contract ReentrancyGuardTransient {
+    using TransientSlot for *;
+
+    // keccak256(abi.encode(uint256(keccak256("openzeppelin.storage.ReentrancyGuard")) - 1)) & ~bytes32(uint256(0xff))
+    bytes32 private constant REENTRANCY_GUARD_STORAGE =
+        0x9b779b17422d0df92223018b32b4d1fa46e071723d6817e2486d003becc55f00;
+
+    /**
+     * @dev Unauthorized reentrant call.
+     */
+    error ReentrancyGuardReentrantCall();
+
+    /**
+     * @dev Prevents a contract from calling itself, directly or indirectly.
+     * Calling a `nonReentrant` function from another `nonReentrant`
+     * function is not supported. It is possible to prevent this from happening
+     * by making the `nonReentrant` function external, and making it call a
+     * `private` function that does the actual work.
+     */
+    modifier nonReentrant() {
+        _nonReentrantBefore();
+        _;
+        _nonReentrantAfter();
+    }
+
+    function _nonReentrantBefore() private {
+        // On the first call to nonReentrant, REENTRANCY_GUARD_STORAGE.asBoolean().tload() will be false
+        if (_reentrancyGuardEntered()) {
+            revert ReentrancyGuardReentrantCall();
+        }
+
+        // Any calls to nonReentrant after this point will fail
+        REENTRANCY_GUARD_STORAGE.asBoolean().tstore(true);
+    }
+
+    function _nonReentrantAfter() private {
+        REENTRANCY_GUARD_STORAGE.asBoolean().tstore(false);
+    }
+
+    /**
+     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
+     * `nonReentrant` function in the call stack.
+     */
+    function _reentrancyGuardEntered() internal view returns (bool) {
+        return REENTRANCY_GUARD_STORAGE.asBoolean().tload();
+    }
+}