[FEATURE] Desktop app: prompt stash (Ctrl+S) parity with TUI

Feature request

The terminal (TUI) version of Claude Code has a prompt stash: pressing Ctrl+S with text in the input stashes it and clears the prompt; pressing it again on an empty prompt restores the stashed text, cursor position, and pasted content (interactive mode docs, action chat:stash in the keybindings reference).

The desktop app (macOS/Windows) has no equivalent. The desktop docs and keybindings reference list no stash action for desktop.

Why it matters

A very common flow: you are mid-way through typing a long prompt, and you need to send a quick different message first (answer a question, stop a task, run a slash command). In the TUI you stash, send, and restore. In the desktop app the only options are manually copying the draft somewhere or losing it.

Proposed behavior

Same as TUI: a keybinding (e.g. Cmd+S / Ctrl+S) that stashes the current composer content and restores it when pressed on an empty composer — ideally preserving cursor position and pasted attachments, as the TUI does.

🤖 Generated with Claude Code