[admin] Add confirmation dialogs for destructive actions in admin dashboard

[coderabbitai]

Background

Currently, destructive actions in the admin dashboard (like deleting messages) lack confirmation dialogs, which could lead to accidental deletions.

Proposed Enhancement

Add confirmation dialogs using AlertDialog component before performing destructive actions to prevent accidental operations.

Context

• Pull Request: feat: admin dashboard #65
• Discussion: feat: admin dashboard #65 (comment)

Implementation Notes

• Use the existing AlertDialog component from the UI library
• Show confirmation dialog before delete operations
• Include clear warning messages about irreversible actions

/cc @jake8655