[BUG] Arrow key navigation in scrollable lists causes terminal to scroll instead of navigating items

Description

When navigating a list in the TUI that exceeds the terminal height, pressing arrow keys (up/down) causes the terminal itself to scroll to the bottom instead of navigating through the list items. This makes it impossible to navigate through long lists.

Steps to Reproduce

1. Open Claude Code TUI
2. Navigate to Plugin Management view (or any view with a list longer than terminal height)
3. Attempt to navigate the list using up/down arrow keys
4. Observe that the terminal scrolls instead of navigating list items

Expected Behavior

The list should automatically scroll internally when the next item to be shown is not visible, while keeping the terminal scroll position fixed. Arrow keys should navigate within the list items without affecting the terminal's scroll buffer.

Actual Behavior

Pressing up/down arrow keys causes the entire terminal to scroll to the bottom, making list navigation impossible.

Environment

• Platform: macOS
• Claude Code Version: 2.0.22
• Terminal: iTerm2 Build 3.6.20250923-nightly
• Reproducibility: Every time (100%)

Additional Context

This issue primarily affects the Plugin Management list view where the list is long enough to exceed terminal height. Other menus may have the same issue but weren't tested with sufficiently long lists.

Workarounds

None found.