[FEATURE] /copy command to copy last response to clipboard

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

Use case:

• Gemini CLI has /copy command
• Useful for long technical explanations
• Avoid manual drag-select in terminal

Proposed Solution

Proposed syntax:
/copy # Copy last assistant response
/copy --all # Copy entire conversation

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_