Add glab api proxy support

[Smasherr]

Feature Request: glab api proxy support

Context

rtk discover identifies glab api as the #1 unhandled command by usage count.

Over the last 30 days across 456 sessions:

• 1,129 invocations of glab api

This is a GitLab CLI (glab) command that returns JSON API responses — often large project metadata, file contents, search results, merge request details, etc. These responses are typically verbose and would benefit significantly from token-optimized filtering.

Example commands

glab api "projects/gitlab-org%2Fcli/merge_requests?state=merged&per_page=5"
glab api "projects/gitlab-org%2Fcli/repository/tree?ref=main&per_page=20"
glab api "projects/gitlab-org%2Fcli/issues?labels=bug&state=opened"
glab api version

Expected behavior

rtk glab should proxy glab api calls and filter/compress the JSON output, similar to how rtk gh handles gh api calls.

Additional context

• glab is the official GitLab CLI (https://gitlab.com/gitlab-org/cli)
• The glab api subcommand is analogous to gh api for GitHub
• Response format is JSON, so existing JSON filtering strategies from rtk gh / rtk curl should be largely reusable
• Also frequently used: glab release (157 invocations) — could be a follow-up

[pszymkowiak]

[w] wshm · Automated triage by AI

🔍 Automated Triage

✨ Category	feature
🟡 Priority	medium
🎯 Confidence	95%

Summary

Request to add glab api proxy support analogous to existing gh api proxy, backed by strong usage data (1,129 invocations across 456 sessions).

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Triaged automatically by wshm · This is an automated analysis, not a human review.

[Smasherr]

Closing in favor of #314 which covers glab support and is adapted to the new codebase structure from #826.