refactor: use fs/promises.copyFile instead of shell exec in createEnvFile

No child process needed for a simple file copy. Uses Node.js native
copyFile which is faster and avoids shell buffering/quoting pitfalls.

Author: fernandomg

source/__tests__/operations/createEnvFile.test.ts

@@ -1,32 +1,34 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
-vi.mock('../../operations/exec.js', () => ({
-  exec: vi.fn().mockResolvedValue(''),
-  execFile: vi.fn().mockResolvedValue(''),
+vi.mock('node:fs/promises', () => ({
+  copyFile: vi.fn().mockResolvedValue(undefined),
 }))
 
-const { exec } = await import('../../operations/exec.js')
+const { copyFile } = await import('node:fs/promises')
 const { createEnvFile } = await import('../../operations/createEnvFile.js')
 
 describe('createEnvFile', () => {
   beforeEach(() => {
     vi.clearAllMocks()
   })
 
-  it('copies .env.example to .env.local', async () => {
+  it('copies .env.example to .env.local in the project folder', async () => {
     await createEnvFile('/project/my_app')
 
-    expect(exec).toHaveBeenCalledWith('cp .env.example .env.local', { cwd: '/project/my_app' })
+    expect(copyFile).toHaveBeenCalledWith(
+      '/project/my_app/.env.example',
+      '/project/my_app/.env.local',
+    )
   })
 
-  it('uses the provided project folder as cwd', async () => {
+  it('uses the provided project folder for both paths', async () => {
     await createEnvFile('/other/path')
 
-    expect(exec).toHaveBeenCalledWith(expect.any(String), { cwd: '/other/path' })
+    expect(copyFile).toHaveBeenCalledWith('/other/path/.env.example', '/other/path/.env.local')
   })
 
-  it('propagates errors from exec', async () => {
-    vi.mocked(exec).mockRejectedValueOnce(new Error('.env.example not found'))
+  it('propagates errors from copyFile', async () => {
+    vi.mocked(copyFile).mockRejectedValueOnce(new Error('.env.example not found'))
 
     await expect(createEnvFile('/project/my_app')).rejects.toThrow('.env.example not found')
   })

source/operations/createEnvFile.ts

@@ -1,5 +1,6 @@
-import { exec } from './exec.js'
+import { copyFile } from 'node:fs/promises'
+import { join } from 'node:path'
 
 export async function createEnvFile(projectFolder: string): Promise<void> {
-  await exec('cp .env.example .env.local', { cwd: projectFolder })
+  await copyFile(join(projectFolder, '.env.example'), join(projectFolder, '.env.local'))
 }