Fork repository PR detection issue - toady fetches upstream PRs instead of fork PRs

[tonyblank]

Issue Description

When using toady in a forked repository, the tool appears to be fetching PRs from the upstream repository instead of the local fork, causing confusion with PR numbering.

Environment

• Repository: Forked repo (eyaltoledano/claude-task-master)
• Command: toady fetch
• Error: "Multiple PRs found but interactive selection not available in JSON mode. Please specify --pr option."

Expected Behavior

• toady should detect and work with PRs in the current forked repository
• PR numbers should correspond to the fork's PR numbers, not upstream

Actual Behavior

• toady appears to be listing PRs from upstream repository
• When specifying --pr 1 (which exists in the fork), toady returns empty results
• The tool lists many PRs (805, 804, etc.) which correspond to upstream, not the fork

Reproduction Steps

1. Clone a forked repository
2. Run toady fetch
3. Observe that PRs listed are from upstream, not fork
4. Try toady fetch --pr 1 where PR 1 exists in fork
5. Get empty results

Additional Context

This appears to be related to how toady determines which repository context to use for GitHub API calls. The fork has its own PR numbering system separate from upstream.

Suggested Fix

toady should respect the current repository context (fork) rather than defaulting to upstream when determining which PRs to fetch.