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/structs/BitMaps.sol

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (utils/structs/BitMaps.sol)
+pragma solidity ^0.8.20;
+
+/**
+ * @dev Library for managing uint256 to bool mapping in a compact and efficient way, provided the keys are sequential.
+ * Largely inspired by Uniswap's https://github.com/Uniswap/merkle-distributor/blob/master/contracts/MerkleDistributor.sol[merkle-distributor].
+ *
+ * BitMaps pack 256 booleans across each bit of a single 256-bit slot of `uint256` type.
+ * Hence booleans corresponding to 256 _sequential_ indices would only consume a single slot,
+ * unlike the regular `bool` which would consume an entire slot for a single value.
+ *
+ * This results in gas savings in two ways:
+ *
+ * - Setting a zero value to non-zero only once every 256 times
+ * - Accessing the same warm slot for every 256 _sequential_ indices
+ */
+library BitMaps {
+    struct BitMap {
+        mapping(uint256 bucket => uint256) _data;
+    }
+
+    /**
+     * @dev Returns whether the bit at `index` is set.
+     */
+    function get(BitMap storage bitmap, uint256 index) internal view returns (bool) {
+        uint256 bucket = index >> 8;
+        uint256 mask = 1 << (index & 0xff);
+        return bitmap._data[bucket] & mask != 0;
+    }
+
+    /**
+     * @dev Sets the bit at `index` to the boolean `value`.
+     */
+    function setTo(BitMap storage bitmap, uint256 index, bool value) internal {
+        if (value) {
+            set(bitmap, index);
+        } else {
+            unset(bitmap, index);
+        }
+    }
+
+    /**
+     * @dev Sets the bit at `index`.
+     */
+    function set(BitMap storage bitmap, uint256 index) internal {
+        uint256 bucket = index >> 8;
+        uint256 mask = 1 << (index & 0xff);
+        bitmap._data[bucket] |= mask;
+    }
+
+    /**
+     * @dev Unsets the bit at `index`.
+     */
+    function unset(BitMap storage bitmap, uint256 index) internal {
+        uint256 bucket = index >> 8;
+        uint256 mask = 1 << (index & 0xff);
+        bitmap._data[bucket] &= ~mask;
+    }
+}