feat: adds support for dark/light mode for the three dots button

[jonybur]

[Copilot]

Pull Request Overview

This PR adds dark/light mode support for the three dots button by conditionally rendering different SVG icons based on the current theme. The implementation uses next-themes to detect the current theme and prevents hydration mismatches with a mounting state.

Key changes:

• Imports two SVG assets for light and dark themes
• Adds theme detection and mounting state management
• Conditionally renders the appropriate icon based on the resolved theme

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[jeremy-babylonlabs]

Why not implement it like the other svg in core-ui?