[Desktop App] Allow customizing Enter key behavior (newline vs submit)

Feature request

The Claude Desktop App for Mac doesn't allow users to customize the Enter key behavior. Enter always submits the message, with no documented way to make it insert a newline instead.

Why this matters

Most modern chat apps (Slack, Discord, Linear, Notion, Cursor, ChatGPT, etc.) let users choose between:

• Enter submits + Shift/Cmd+Enter for newline (chat-style)
• Enter newline + Shift/Cmd+Enter to submit (editor-style)

When composing longer prompts (multi-paragraph, code-heavy, structured), accidentally pressing Enter and submitting an unfinished message is a constant frustration. Users developed muscle memory from tools where Enter = newline.

Current state

• Claude Code CLI: works perfectly via ~/.claude/keybindings.json with chat:newline / chat:submit bindings.
• Claude Desktop App: ignores ~/.claude/keybindings.json. No equivalent setting in ~/Library/Application Support/Claude/config.json or in the Settings UI.

Workarounds users currently need

• Karabiner-Elements per-app key remapping (third-party tool installation)
• macOS App Shortcuts (only works if app exposes a corresponding menu item)

Proposed solution

Add a setting to the Desktop App preferences:

• Enter key behavior: Submit message (default) | Insert newline
• When set to "Insert newline", Cmd+Enter submits.

Or simply honor ~/.claude/keybindings.json in the Desktop App, same as the CLI.

Environment

• Claude Desktop App for Mac (com.anthropic.claudefordesktop)
• macOS