aisman

Session 157, Step 3: Add Shift-modifier multi-highlight arrow navigation to main lists
- AIM-2971 Add Shift-modifier multi-highlight arrow navigation to main lists
- AIM-2974 Add Up/Down arrow list navigation shortcuts
- AIM-2975 Add Left/Right arrow shortcuts for list history navigation
- AIM-2956 Show shortcut feedback for Esc/Enter on confirm2/alert2 dialogs

Outcome:
All four issues implemented and validated.

- **AIM-2971** (issue 3469): Shift+Up/Down now deselects the outermost highlight when direction reverses, instead of always adding.
- **AIM-2974** (issue 3472): Plain Left/Right now navigates history like Ctrl+Left/Right (modifying the nav/fwd stacks, updating toolbar buttons) but only highlights without loading detail. Enter confirms, Esc restores.
- **AIM-2975** (issue 3473): Same Left/Right preview navigation fix across all three lists.
- **issue -3564**: Shortcut visual feedback rectangle shown on Enter/Esc in confirm2/alert2 dialogs with the actual button caption.