[WIP] Fix detection issues for pull requests

[Copilot]

Thanks for the feedback on #4629. I've created this new PR, which merges into #4629, to address your comment. I will work on the changes and keep this PR's description up to date as I make progress.

Original PR: #4629
Triggering comment (#4629 (comment)):

@copilot address comments and fix the broken tests

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[osortega]

@copilot Try again

[Copilot]

@copilot Try again

Done in ed67f82. Fixed the broken tests and addressed the review comments:

1. Root cause of test timeouts: detectPullRequestWithRetry had no pre-checks, so it always incurred 2s+4s+8s=14s of delays even for sessions without a worktree branch or GitHub remote. Added two pre-checks to return early:

   • Skip if session has no worktree branch/repository path
   • Skip if the repository has no GitHub remote (checked via getGitHubRepoInfoFromContext)

2. processPendingPrDetections: Reverted from Promise.all parallel execution to a sequential for...of loop per the "revert this change" comment.

3. New unit tests: Added PR detection retry behavior describe block with 3 tests using vi.useFakeTimers() to verify the retry schedule.