Complete TUI Phase 3 implementation with all 5 power feature screens:
- Who screen: 5 modes (expert/workload/reviews/active/overlap) with
mode tabs, input bar, result rendering, and hint bar
- Search screen: full-text search with result list and scoring display
- Timeline screen: chronological event feed with time-relative display
- Trace screen: file provenance chains with expand/collapse, rename
tracking, and linked issues/discussions
- File History screen: per-file MR timeline with rename chain display
and discussion snippets
Also includes:
- Command palette overlay (fuzzy search)
- Bootstrap screen (initial sync flow)
- Action layer split from monolithic action.rs to per-screen modules
- Entity and render cache infrastructure
- Shared who_types module in core crate
- All screens wired into view/mod.rs dispatch
- 597 tests passing, clippy clean (pedantic + nursery), fmt clean
