feat: add import-gh-token command for SSO-enabled organizations

[bahag-chaurasiak]

Summary

Adds a new CLI command repobar import-gh-token that imports the authentication token from GitHub CLI (gh) into RepoBar's keychain.

This is useful for users in SSO-enabled organizations where:

• The gh CLI is already authorized for their org via SAML SSO
• RepoBar's built-in OAuth flow can't get org access (requires org admin approval for third-party OAuth apps)

Usage

repobar import-gh-token

How it works

1. Reads the token from gh auth token
2. Stores it in RepoBar's keychain with a 1-year expiry
3. Works with both the CLI and the menu bar app (shared keychain)

Prerequisites

• GitHub CLI must be installed (brew install gh)
• User must be logged in via gh (gh auth login)
• The gh token should have SSO authorization for the target org

Test plan

• Build and run repobar import-gh-token
• Verify token is imported successfully
• Verify repobar list shows organization repos
• Verify menu bar app shows organization repos
• Verify repobar import-gh-token --help shows usage info

Fixes #2

[steipete]

Landed via temp rebase onto main.\n\n- Gate: pnpm lint && pnpm build && pnpm test\n- Land commit: bcc272096b5ab86f44d9a2aa0f8157d968e48c0f\n- Merge commit: 226046c\n\nThanks @bahag-chaurasiak!