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/@nomicfoundation/hardhat-utils/src/subprocess.ts

@@ -0,0 +1,46 @@
+import { spawn } from "node:child_process";
+
+import {
+  SubprocessFileNotFoundError,
+  SubprocessPathIsDirectoryError,
+} from "./errors/subprocess.js";
+import { exists, isDirectory } from "./fs.js";
+
+/**
+ * Spawns a detached subprocess to execute a given file with optional arguments.
+ *
+ * @param absolutePathToSubProcessFile - The absolute path to the subprocess file to be executed.
+ * @param args - Optional list of string arguments to pass to the subprocess.
+ * @param env - Optional environment key-value pairs to pass to the subprocess.
+ *
+ * The subprocess runs in a detached mode and its standard input/output is ignored.
+ * This function does not wait for the subprocess to complete and the subprocess is unreferenced
+ * to allow the parent process to exit independently.
+ */
+export async function spawnDetachedSubProcess(
+  absolutePathToSubProcessFile: string,
+  args: string[] = [],
+  env: Record<string, string> = {},
+): Promise<void> {
+  if ((await exists(absolutePathToSubProcessFile)) === false) {
+    throw new SubprocessFileNotFoundError(absolutePathToSubProcessFile);
+  }
+
+  if ((await isDirectory(absolutePathToSubProcessFile)) === true) {
+    throw new SubprocessPathIsDirectoryError(absolutePathToSubProcessFile);
+  }
+
+  const subprocessArgs = [absolutePathToSubProcessFile, ...args];
+
+  if (absolutePathToSubProcessFile.endsWith(".ts")) {
+    subprocessArgs.unshift("--import", import.meta.resolve("tsx/esm"));
+  }
+
+  const subprocess = spawn(process.execPath, subprocessArgs, {
+    detached: true,
+    env,
+    stdio: "ignore",
+  });
+
+  subprocess.unref();
+}