[FEATURE] Enter key should insert newline, Cmd+Enter should send message

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When composing a multi-line message, pressing Enter accidentally sends the message before I'm done writing. This is especially frustrating on Japanese keyboards where Enter is frequently used for text input confirmation (IME).

Proposed Solution

Add a setting to change the send shortcut:

• Enter: insert newline
• Cmd+Enter (Mac) / Ctrl+Enter (Windows): send message

This is the same behavior as Slack's "Enter key preference" setting.

Alternative Solutions

Currently using third-party tools like Enter Guard or Chrome extensions as workarounds.

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

When writing a long prompt with multiple paragraphs, I press Enter to add a newline but the message gets sent accidentally.

Additional Context

_No response_