Add a gitignore-aware repository tree with search and open-file navigation #29
Description
Problem
Operators need a real workspace tree so sessions can browse and attach repository context without leaving the app.
Scope
- Add tree navigation, filtering, fuzzy search, and open-file behavior
- Respect .gitignore and app-specific ignore rules
- Define performance expectations for medium and large repos
Out of scope
- Re-creating basic .gitignore files that already exist in the repo
- Monaco editor implementation details beyond tree-to-open-file behavior
Implementation notes
- Keep the repository tree tightly integrated with attachments and file viewing
- Make repo browsing an operator feature, not just a coding-only affordance
- Preserve desktop-first usability
Definition of Done
- The issue explicitly defines tree behavior, ignore behavior, and file-opening expectations
- Performance expectations are concrete enough for later testing
Verification
- Review the issue against the feature spec operator flow