`spawn("npm", ...)` fails on Windows — missing `shell: true` or `.cmd` suffix

[MadhushaPrasad]

Description:
installDependencies.ts uses spawn("npm", ["install"], { cwd }). On Windows, the npm executable is npm.cmd, not npm. Calling spawn without shell: true will throw an ENOENT error on Windows, making dependency installation completely broken for Windows users.

File: installDependencies.ts

Expected: Pass { shell: true } in the spawn options, which works cross-platform on macOS, Linux, and Windows without needing OS detection.