[UX] Can't switch model without clearing typed input — need keybinding or inline shortcut

Problem Statement

When a message is already typed and ready to send, switching models requires:

1. Clearing the entire input
2. Typing /model and selecting a model
3. Retyping or pasting the original message back

Expected Behavior

Be able to switch models without losing the current input — e.g.:

• A keyboard shortcut to open the model picker while keeping the input intact
• An inline model selector in the input bar (like /model but without clearing)
• A flag on message send (e.g. /send --model sonnet)

Actual Behavior

/model is a standalone slash command that replaces the entire input.

Related

#63683 (general model switcher request)