Feature request: vim-style keyboard scrolling for chat history

Problem

There's no way to scroll through chat history using only the keyboard. Page Up/Page Down don't work, and there are no vim-style scroll keybindings.

Currently the only option is mouse scroll, which breaks the keyboard-driven workflow that makes Claude Code appealing.

Suggested solution

Add scroll keybindings for navigating chat history:

• Ctrl+u / Ctrl+d for half-page up/down
• Ctrl+b / Ctrl+f for full page up/down
• Or simply make Page Up/Page Down work

This would complement the existing /vim mode and fit the tool's developer-focused, keyboard-centric design.

Alternatives considered

• Terminal emulator scrollback doesn't work well since Claude Code is a TUI that redraws the screen
• /export to dump conversation and read in vim works but is clunky for quick review
• Esc Esc rewind is useful but isn't scrolling