[Bug]: New-project repository lookup fails for self-hosted GitLab when given a full URL — entire URL is sent as the project path to `glab api projects/<encoded-url>`

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

1. Authenticate glab against a self-hosted GitLab whose hostname does not contain "gitlab" (for example sourcecontrol.example.com) and set it as the default host.
2. In t3 code, enable GitLab source control (it correctly detects the authenticated host).
3. Start a new project, select GitLab, and paste the full repository URL: https://sourcecontrol.example.com/group/project
4. Observe the error.

Expected behavior

t3 code normalizes the full URL to the group/project path and looks the repository up successfully, the same way it does for gitlab.com URLs.

Actual behavior

Lookup fails: "Source control repository operation lookupRepository failed for gitlab: The source control operation could not be completed."

Impact

Minor bug or occasional failure

Version or commit

No response

Environment

• t3 code: Alpha (Windows build dated 2026-08-10) - OS: Windows 11 - glab: 1.102.0 - GitLab: self-managed, host sourcecontrol.example.com (hostname does not contain "gitlab") - glab authenticated and set as default host: - glab auth status → ✓ Logged in to sourcecontrol.example.com - glab config get host → sourcecontrol.example.com

Logs or stack traces

Screenshots, recordings, or supporting files

No response

Workaround

Enter the bare namespace/project path instead of the URL:

group/project

This resolves and clones correctly, because the server relies on glab's default host and the path maps to a valid glab api projects/<encoded-path> call.

Start in apps/desktop and trace the GitLab source-control repository lookup, comparing full-URL handling with the existing gitlab.com behavior. Reproduce with a self-hosted host such as sourcecontrol.example.com and verify that the full URL resolves as group/project while the bare path continues to work.