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/Blockhash.sol

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.4.0) (utils/Blockhash.sol)
+pragma solidity ^0.8.20;
+
+/**
+ * @dev Library for accessing historical block hashes beyond the standard 256 block limit.
+ * Uses EIP-2935's history storage contract which maintains a ring buffer of the last
+ * 8191 block hashes in state.
+ *
+ * For blocks within the last 256 blocks, it uses the native `BLOCKHASH` opcode.
+ * For blocks between 257 and 8191 blocks ago, it queries the EIP-2935 history storage.
+ * For blocks older than 8191 or future blocks, it returns zero, matching the `BLOCKHASH` behavior.
+ *
+ * NOTE: After EIP-2935 activation, it takes 8191 blocks to completely fill the history.
+ * Before that, only block hashes since the fork block will be available.
+ */
+library Blockhash {
+    /// @dev Address of the EIP-2935 history storage contract.
+    address internal constant HISTORY_STORAGE_ADDRESS = 0x0000F90827F1C53a10cb7A02335B175320002935;
+
+    /**
+     * @dev Retrieves the block hash for any historical block within the supported range.
+     *
+     * NOTE: The function gracefully handles future blocks and blocks beyond the history window
+     * by returning zero, consistent with the EVM's native `BLOCKHASH` behavior.
+     */
+    function blockHash(uint256 blockNumber) internal view returns (bytes32) {
+        uint256 current = block.number;
+        uint256 distance;
+
+        unchecked {
+            // Can only wrap around to `current + 1` given `block.number - (2**256 - 1) = block.number + 1`
+            distance = current - blockNumber;
+        }
+
+        return distance < 257 ? blockhash(blockNumber) : _historyStorageCall(blockNumber);
+    }
+
+    /// @dev Internal function to query the EIP-2935 history storage contract.
+    function _historyStorageCall(uint256 blockNumber) private view returns (bytes32 hash) {
+        assembly ("memory-safe") {
+            // Store the blockNumber in scratch space
+            mstore(0x00, blockNumber)
+            mstore(0x20, 0)
+
+            // call history storage address
+            pop(staticcall(gas(), HISTORY_STORAGE_ADDRESS, 0x00, 0x20, 0x20, 0x20))
+
+            // load result
+            hash := mload(0x20)
+        }
+    }
+}