fix: search issues returns empty results

[q-soriarty]

Problem

`copia-cli search issues test` returns empty results even when matching issues exist.

Root cause

The search issues command uses the per-repo Gitea endpoint `/repos/{owner}/{repo}/issues?q=` which requires a repo context. The `gh` CLI uses a global search endpoint.

Gitea's global search endpoint for issues may differ from what's currently implemented, or the test repo's issues may not be indexed for search.

Affected command

• `search issues `
• `search issues --limit N`
• `search issues --json`

Possible fixes

1. Verify the correct Gitea search endpoint for issues
2. Consider using `/repos/{owner}/{repo}/issues?q=&type=issues` or the global `/repos/search` with issue filtering
3. If search requires repo context, document this difference vs `gh search issues`

Discovered by

gh CLI behavior comparison test.

[github-actions]

Closed by #123 (merged into develop).