Vim mode: j/k and / should work for history navigation in normal mode

Description

In vim mode, normal-mode keys that every vim-mode shell maps to history navigation do nothing useful in Claude Code:

• j/k - should navigate input history (up/down), currently move cursor to end/beginning of line, duplicating $/0 which already work
• / - should search input history (like reverse-search), currently does nothing

In bash (set -o vi), zsh vi-mode, and fish, these are standard behaviors.

Current behavior

• j/k move cursor to end/beginning of the current line (redundant with $/0)
• / does nothing
• History navigation requires arrow keys or Ctrl+R

Expected behavior

• j/k in normal mode navigate through previous inputs
• / in normal mode searches input history

Prior issue

This was previously requested (j/k part) in #4296, which was auto-closed after 60 days without any response. Would be great to know whether this is on the roadmap.