Add GitLab Integration

[vcanuel]

Hey! Really enjoying Vibe Kanban so far.

Problem

Right now vibe-kanban only supports GitHub repositories. Teams using GitLab (whether cloud or self-hosted) can't use the tool, which limits adoption for projects already on that platform.

Request

Could we add GitLab support alongside the existing GitHub integration? This would include connecting to GitLab repos, syncing issues/merge requests, and supporting both gitlab.com and self-hosted instances.

Why this helps

• Expands the tool to a significant portion of the dev community
• Supports teams with self-hosted GitLab instances
• Makes vibe-kanban more platform-agnostic and flexible
• Allows mixed teams (GitHub + GitLab) to use the same workflow tool