[FEATURE] Allow deleting individual chat messages

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

Sometimes I send a message by mistake or want to remove it from the chat history, but there's no way to delete my own individual messages.

Proposed Solution

Add an X button on each of my own messages to delete it from the chat.

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_