[Feature]: Support slash command in ACP mode

[quan-ngo-ts]

What would you like to be added?

Currently, when running Auggie in ACP mode, slash commands such as /stats are treated as regular prompts instead of being recognized and executed as commands.

The Auggie CLI should:

• Clearly advertise the list of available slash commands while in ACP mode.
• Properly parse and handle slash commands (e.g., /stats) instead of forwarding them as normal prompts.

Why is this needed?

This enhancement is necessary to fully utilize Auggie’s capabilities in ACP mode. Without proper slash command support, key CLI features remain inaccessible or inconsistent, limiting the effectiveness of ACP-based workflows.

Possible solution or alternatives

No

Additional context

No response