Feature request: add a redo action (chat:redo) for the prompt input

Summary

The keybindings system exposes chat:undo (undo last edit in the prompt input) but there's no corresponding redo action. This means an accidental undo can't be reversed.

Request

Add a chat:redo action to the Chat context so it can be bound to a key (e.g. Ctrl+Y or Ctrl+Shift+-), mirroring the standard undo/redo pairing found in most editors.

Current behavior

chat:undo (default Ctrl+_, Ctrl+Shift+-) is the only prompt-edit history action available. Verified against the keybindings docs — no redo action exists.

Environment

• Platform: macOS (darwin 25.5.0)