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/hardhat/templates/hardhat-3/02-mocha-ethers/contracts/Counter.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.28;
+
+contract Counter {
+  uint public x;
+
+  event Increment(uint by);
+
+  function inc() public {
+    x++;
+    emit Increment(1);
+  }
+
+  function incBy(uint by) public {
+    require(by > 0, "incBy: increment should be positive");
+    x += by;
+    emit Increment(by);
+  }
+}

dev/env/node_modules/hardhat/templates/hardhat-3/02-mocha-ethers/contracts/Counter.t.sol

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.28;
+
+import {Counter} from "./Counter.sol";
+import {Test} from "forge-std/Test.sol";
+
+// Solidity tests are compatible with foundry, so they
+// use the same syntax and offer the same functionality.
+
+contract CounterTest is Test {
+  Counter counter;
+
+  function setUp() public {
+    counter = new Counter();
+  }
+
+  function test_InitialValue() public view {
+    require(counter.x() == 0, "Initial value should be 0");
+  }
+
+  function testFuzz_Inc(uint8 x) public {
+    for (uint8 i = 0; i < x; i++) {
+      counter.inc();
+    }
+    require(counter.x() == x, "Value after calling inc x times should be x");
+  }
+
+  function test_IncByZero() public {
+    vm.expectRevert();
+    counter.incBy(0);
+  }
+}