[BUG] Slash commands selected while message is queued are sent as plain text to Claude

Bug Description

When a message is queued (i.e., typed while Claude is still responding), the slash command autocomplete menu appears as expected when typing /. However, selecting a slash command (e.g., /model) causes it to be sent as a plain text message to Claude rather than being executed as a command.

Steps to Reproduce

1. Send a message so Claude is actively responding
2. While Claude is responding, type / in the input field — the slash command menu appears
3. Select a command (e.g., /model) from the menu
4. The command is queued and then delivered as a literal text message to Claude instead of being handled as a slash command

Expected Behavior

Slash commands selected in "queue next message" mode should be executed as commands when the queue is processed.

Actual Behavior

The slash command is treated as plain text and sent as a user message to Claude.

Environment

• Claude Code CLI (terminal, not VS Code extension)
• Linux