fix: prevent ssh hang during login and improve browser fallback

[Huerte]

Type

• Bug fix
• New feature
• Documentation
• Refactor / internal

Overview

This fixes a bug where gitgo user login would freeze forever if the user's ssh agent wasn't running. the ssh command was waiting for a passphrase, but because we capture the output, the prompt was invisible. i also fixed the browser auto-open so it prints the github url if the browser fails to open.

Changes

• ssh_utils.py: added BatchMode=yes, timeouts, and stdin=DEVNULL to the ssh connection checks so they fail fast instead of hanging.
• ssh_utils.py: updated the open_github_settings function to catch errors and always print the target url as a fallback.
• manager.py: changed the login flow so the browser opens instantly, and improved the error messages if login fails.

How to Test

1. pip install -e ".[dev]"
2. run gitgo user login
3. see that it doesn't freeze anymore and properly reports that the login failed.
4. Expected result: the tool should open the browser (or print the url) and eventually return a clear error message instead of hanging forever.

Checklist

• I tested my changes locally and they work
• I updated CHANGELOG.md under the [Unreleased] section
• I updated README.md (if I added or changed a command)
• I added or updated tests for my change (if applicable)
• My change does not break any existing commands (if it does, describe the impact in the Overview)