feat(performance): Add async utility functions and filesystem utilities

- Implemented async utilities including delay, retryWithBackoff, withTimeout, parallelLimit, debounceAsync, AsyncMutex, and CircuitBreaker.
- Created tests for async utilities to ensure functionality and reliability.
- Developed AsyncFileSystem class with methods for file and directory operations, including ensureDir, readFile, writeFile, remove, and more.
- Added tests for filesystem utilities to validate file operations and error handling.

test/core/utils/test.fs-utils.ts

@@ -0,0 +1,185 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import * as path from 'path';
+import { AsyncFileSystem } from '../../../ts/core/utils/fs-utils.js';
+
+// Use a temporary directory for tests
+const testDir = path.join(process.cwd(), '.nogit', 'test-fs-utils');
+const testFile = path.join(testDir, 'test.txt');
+const testJsonFile = path.join(testDir, 'test.json');
+
+tap.test('should create and check directory existence', async () => {
+  // Ensure directory
+  await AsyncFileSystem.ensureDir(testDir);
+  
+  // Check it exists
+  const exists = await AsyncFileSystem.exists(testDir);
+  expect(exists).toBeTrue();
+  
+  // Check it's a directory
+  const isDir = await AsyncFileSystem.isDirectory(testDir);
+  expect(isDir).toBeTrue();
+});
+
+tap.test('should write and read text files', async () => {
+  const testContent = 'Hello, async filesystem!';
+  
+  // Write file
+  await AsyncFileSystem.writeFile(testFile, testContent);
+  
+  // Check file exists
+  const exists = await AsyncFileSystem.exists(testFile);
+  expect(exists).toBeTrue();
+  
+  // Read file
+  const content = await AsyncFileSystem.readFile(testFile);
+  expect(content).toEqual(testContent);
+  
+  // Check it's a file
+  const isFile = await AsyncFileSystem.isFile(testFile);
+  expect(isFile).toBeTrue();
+});
+
+tap.test('should write and read JSON files', async () => {
+  const testData = {
+    name: 'Test',
+    value: 42,
+    nested: {
+      array: [1, 2, 3]
+    }
+  };
+  
+  // Write JSON
+  await AsyncFileSystem.writeJSON(testJsonFile, testData);
+  
+  // Read JSON
+  const readData = await AsyncFileSystem.readJSON(testJsonFile);
+  expect(readData).toEqual(testData);
+});
+
+tap.test('should copy files', async () => {
+  const copyFile = path.join(testDir, 'copy.txt');
+  
+  // Copy file
+  await AsyncFileSystem.copyFile(testFile, copyFile);
+  
+  // Check copy exists
+  const exists = await AsyncFileSystem.exists(copyFile);
+  expect(exists).toBeTrue();
+  
+  // Check content matches
+  const content = await AsyncFileSystem.readFile(copyFile);
+  const originalContent = await AsyncFileSystem.readFile(testFile);
+  expect(content).toEqual(originalContent);
+});
+
+tap.test('should move files', async () => {
+  const moveFile = path.join(testDir, 'moved.txt');
+  const copyFile = path.join(testDir, 'copy.txt');
+  
+  // Move file
+  await AsyncFileSystem.moveFile(copyFile, moveFile);
+  
+  // Check moved file exists
+  const movedExists = await AsyncFileSystem.exists(moveFile);
+  expect(movedExists).toBeTrue();
+  
+  // Check original doesn't exist
+  const originalExists = await AsyncFileSystem.exists(copyFile);
+  expect(originalExists).toBeFalse();
+});
+
+tap.test('should list files in directory', async () => {
+  const files = await AsyncFileSystem.listFiles(testDir);
+  
+  expect(files).toContain('test.txt');
+  expect(files).toContain('test.json');
+  expect(files).toContain('moved.txt');
+});
+
+tap.test('should list files with full paths', async () => {
+  const files = await AsyncFileSystem.listFilesFullPath(testDir);
+  
+  const fileNames = files.map(f => path.basename(f));
+  expect(fileNames).toContain('test.txt');
+  expect(fileNames).toContain('test.json');
+  
+  // All paths should be absolute
+  files.forEach(file => {
+    expect(path.isAbsolute(file)).toBeTrue();
+  });
+});
+
+tap.test('should get file stats', async () => {
+  const stats = await AsyncFileSystem.getStats(testFile);
+  
+  expect(stats).not.toBeNull();
+  expect(stats?.isFile()).toBeTrue();
+  expect(stats?.size).toBeGreaterThan(0);
+});
+
+tap.test('should handle non-existent files gracefully', async () => {
+  const nonExistent = path.join(testDir, 'does-not-exist.txt');
+  
+  // Check existence
+  const exists = await AsyncFileSystem.exists(nonExistent);
+  expect(exists).toBeFalse();
+  
+  // Get stats should return null
+  const stats = await AsyncFileSystem.getStats(nonExistent);
+  expect(stats).toBeNull();
+  
+  // Remove should not throw
+  await AsyncFileSystem.remove(nonExistent);
+});
+
+tap.test('should remove files', async () => {
+  // Remove a file
+  await AsyncFileSystem.remove(testFile);
+  
+  // Check it's gone
+  const exists = await AsyncFileSystem.exists(testFile);
+  expect(exists).toBeFalse();
+});
+
+tap.test('should ensure file exists', async () => {
+  const ensureFile = path.join(testDir, 'ensure.txt');
+  
+  // Ensure file
+  await AsyncFileSystem.ensureFile(ensureFile);
+  
+  // Check it exists
+  const exists = await AsyncFileSystem.exists(ensureFile);
+  expect(exists).toBeTrue();
+  
+  // Check it's empty
+  const content = await AsyncFileSystem.readFile(ensureFile);
+  expect(content).toEqual('');
+});
+
+tap.test('should recursively list files', async () => {
+  // Create subdirectory with file
+  const subDir = path.join(testDir, 'subdir');
+  const subFile = path.join(subDir, 'nested.txt');
+  
+  await AsyncFileSystem.ensureDir(subDir);
+  await AsyncFileSystem.writeFile(subFile, 'nested content');
+  
+  // List recursively
+  const files = await AsyncFileSystem.listFilesRecursive(testDir);
+  
+  // Should include files from subdirectory
+  const fileNames = files.map(f => path.relative(testDir, f));
+  expect(fileNames).toContain('test.json');
+  expect(fileNames).toContain(path.join('subdir', 'nested.txt'));
+});
+
+tap.test('should clean up test directory', async () => {
+  // Remove entire test directory
+  await AsyncFileSystem.removeDir(testDir);
+  
+  // Check it's gone
+  const exists = await AsyncFileSystem.exists(testDir);
+  expect(exists).toBeFalse();
+});
+
+tap.start();