Slack init command doesn't use packageManager from package.json

Description

When running the slack init command the CLI doesn't use the packageManager defined by the user in package.json. This causes it to hang and reinstall all dependencies using npm.

Version

v3.5.1

OS Info

ProductName:            macOS
ProductVersion:         15.5
BuildVersion:           24F74
Darwin Kernel Version 24.5.0: Tue Apr 22 19:54:49 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6000

Steps to reproduce:

Share the commands to run, source code, and project settings:

1. Run slack init -v in your project.
2. View logs to see npm is used.
3. Command takes a long time.

Expected result:

1. Slack CLI detects packageManager
2. Slack CLI runs commands using this packageManager
3. If @slack/cli-hooks are already installed the command takes milliseconds.

Actual result:

npm is used and the command takes very long

Requirements

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.

Start by reproducing slack init -v in a project with a package.json packageManager field and inspect the init path that invokes dependency installation. Verify which package manager is selected and whether installed @slack/cli-hooks dependencies are reused; done means init uses the declared manager without unnecessary reinstalls.