/diff view can't be scrolled with keyboard

Bug

The /diff slash command opens a scrollable diff pane (uncommitted-changes view). When the diff is taller than the viewport, the only way to scroll is with the mouse / trackpad — no keyboard keys work.

Tested keys (none scroll):

• j / k
• ↑ / ↓
• PgUp / PgDn
• Space / Shift+Space

The footer only shows ← to back · Esc to back, no scroll affordance is hinted. The scroll-down arrow visible at the bottom-right corner of the pane (see screenshot) implies scrolling is supported — but only mouse works.

Expected

j / k scroll the diff content, to match Claude Code's existing keyboard-navigation pattern elsewhere in the UI. ↑ / ↓ and PgUp / PgDn as additional bindings would also be nice.

Repro

1. Make a diff longer than one screen.
2. Run /diff.
3. Try to scroll with any key — nothing scrolls. Only the mouse wheel / trackpad works.

Environment

• Claude Code v2.1.144
• macOS, Ghostty terminal

<img width="2000" height="1125" alt="Image" src="https://github.com/user-attachments/assets/8f54561b-abe9-41e3-b2f7-9ec9882b07a2" />