fix: replace Bun-specific APIs with Node.js APIs for npm compatibility

- Replace Bun.spawn with exec from child_process in extract.ts
- Replace Bun.file().exists() with access from fs/promises
- Replace Bun.write with writeFile from fs/promises in github.ts
- Add cp and rm from fs/promises for file operations
- Bump version to 1.0.2

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

cli/src/utils/github.ts

@@ -1,3 +1,4 @@
+import { writeFile } from 'node:fs/promises';
 import type { Release } from '../types/index.js';
 
 const REPO_OWNER = 'nextlevelbuilder';
@@ -50,7 +51,7 @@ export async function downloadRelease(url: string, dest: string): Promise<void>
   }
 
   const buffer = await response.arrayBuffer();
-  await Bun.write(dest, buffer);
+  await writeFile(dest, Buffer.from(buffer));
 }
 
 export function getAssetUrl(release: Release): string | null {