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/token/ERC721/utils/ERC721Holder.sol

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/utils/ERC721Holder.sol)
+
+pragma solidity ^0.8.20;
+
+import {IERC721Receiver} from "../IERC721Receiver.sol";
+
+/**
+ * @dev Implementation of the {IERC721Receiver} interface.
+ *
+ * Accepts all token transfers.
+ * Make sure the contract is able to use its token with {IERC721-safeTransferFrom}, {IERC721-approve} or
+ * {IERC721-setApprovalForAll}.
+ */
+abstract contract ERC721Holder is IERC721Receiver {
+    /**
+     * @dev See {IERC721Receiver-onERC721Received}.
+     *
+     * Always returns `IERC721Receiver.onERC721Received.selector`.
+     */
+    function onERC721Received(address, address, uint256, bytes memory) public virtual returns (bytes4) {
+        return this.onERC721Received.selector;
+    }
+}

dev/env/node_modules/@openzeppelin/contracts/token/ERC721/utils/ERC721Utils.sol

@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.4.0) (token/ERC721/utils/ERC721Utils.sol)
+
+pragma solidity ^0.8.20;
+
+import {IERC721Receiver} from "../IERC721Receiver.sol";
+import {IERC721Errors} from "../../../interfaces/draft-IERC6093.sol";
+
+/**
+ * @dev Library that provide common ERC-721 utility functions.
+ *
+ * See https://eips.ethereum.org/EIPS/eip-721[ERC-721].
+ *
+ * _Available since v5.1._
+ */
+library ERC721Utils {
+    /**
+     * @dev Performs an acceptance check for the provided `operator` by calling {IERC721Receiver-onERC721Received}
+     * on the `to` address. The `operator` is generally the address that initiated the token transfer (i.e. `msg.sender`).
+     *
+     * The acceptance call is not executed and treated as a no-op if the target address doesn't contain code (i.e. an EOA).
+     * Otherwise, the recipient must implement {IERC721Receiver-onERC721Received} and return the acceptance magic value to accept
+     * the transfer.
+     */
+    function checkOnERC721Received(
+        address operator,
+        address from,
+        address to,
+        uint256 tokenId,
+        bytes memory data
+    ) internal {
+        if (to.code.length > 0) {
+            try IERC721Receiver(to).onERC721Received(operator, from, tokenId, data) returns (bytes4 retval) {
+                if (retval != IERC721Receiver.onERC721Received.selector) {
+                    // Token rejected
+                    revert IERC721Errors.ERC721InvalidReceiver(to);
+                }
+            } catch (bytes memory reason) {
+                if (reason.length == 0) {
+                    // non-IERC721Receiver implementer
+                    revert IERC721Errors.ERC721InvalidReceiver(to);
+                } else {
+                    assembly ("memory-safe") {
+                        revert(add(reason, 0x20), mload(reason))
+                    }
+                }
+            }
+        }
+    }
+}