[vegeris]

Changelog

Added the slack sandbox signup command to join the Slack Developer Program using an account you're already logged in to with the CLI. Your name and email are read from that account's Slack profile, and the terms are confirmed in the terminal or with the --accept-tos flag.

Summary

This PR adds an authenticated slack sandbox signup command.

• The account comes from --token, the --team flag, or a prompt listing your logins with their email addresses. If you aren't logged in to any accounts, it errors with not_authed and suggests slack login.
• The terms (Privacy Policy, API Terms of Service, Developer Program Agreement) are shown with a confirm prompt unless --accept-tos or --force is passed.
• First and last names are prefilled from the Slack profile, falling back to splitting real_name, and are only prompted for when missing. --postal-code, --country, and --newsletter are optional flags.
• On success it suggests slack sandbox create.

Other changes:

• internal/api: adds SignupRequest, SignupVerifiedResponse, and SignupDeveloperProgramVerified, plus a mock and tests.
• types.UserProfile: adds the first_name, last_name, and real_name fields from users.info.
• Regenerated the command reference docs.

Preview

Testing

1. Build the CLI with make build.
2. Log in to a workspace using an email that isn't already linked to a developer account.
3. Run sandbox signup, select an auth, and accept the terms. The details summary shows your name and email.
4. Run sandbox create and confirm that a sandbox was created.
5. Run sandbox signup --team <team-id> --accept-tos --first-name Ada --last-name Lovelace --country us and confirm that no prompts appear and the country shows as US.

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.