fix: Show both local and remote repo name when they differ

[charlesvien]

Problem

Folder display names only used path.basename(), so when a local directory name differed from the GitHub repo name, the dropdown showed one name and the sidebar showed another.

Closes #1283

Changes

1. Add getDisplayName that appends remote repo name when it differs from the local dir (e.g. ph-tour-demo (hogotchi))
2. Extract shared normalizeRepoKey helper to strip .git suffixes consistently
3. Use normalizeRepoKey in sidebar folder matching to fix .git suffix mismatches
4. Use folder.name instead of group.name in sidebar labels for consistency
5. Add four unit tests covering suffix stripping, mismatch, match and case-insensitive match

How did you test this?

Manually

[charlesvien]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• fix: Fix stale context usage after compaction + usage calculation #1548
• fix: Show both local and remote repo name when they differ #1547 👈 (View in Graphite)
• fix: Queue messages during conversation compaction #1546
• fix: Prevent permission request from stealing focus across cells #1545
• feat: Add double-click to rename task title in session header #1544
• fix: Reduce unnecessary IPC calls causing UI unresponsiveness #1542
• fix: Move folder cleanup and orphaned worktree pruning to main process #1541
• fix: Show "edit" instead of "create" in permission prompt for existing files #1538
• fix: Remove double scrollbar from repo selector #1537
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.