Feature request: j/k vim navigation in /diff file picker (consistent with /plugin)

Feature request

Add j/k vim-style navigation to the /diff command's file picker, to make it consistent with the rest of the Claude Code CLI.

Why

Most navigable list screens in the CLI already accept j/k as aliases for ↓/↑ — /plugin is the canonical example. The /diff file picker is an exception: only the arrow keys move the selection. Reaching for arrows after living in j/k everywhere else in the CLI breaks flow.

Repro

1. In a repo with uncommitted changes affecting several files, run /diff.
2. Try j and k to move the selection between files.
3. Observe that nothing happens — only ↑/↓ work.

Screenshot

The footer of the /diff picker shows ↑/↓ to select — would expect ↑/↓/j/k to select (or equivalent) here, matching the other list UIs.

!/diff file picker

Ask

Wire j/k as additional bindings on the /diff file list — same handler as ↓/↑. Ideally apply the same treatment to any other list screen that still only accepts arrows, so the vim navigation contract is universal across the CLI.

Thanks!