FEAT: change admin menu icon default color

[LenVan]

Description of the Change

The current SVG icon used in add_menu_page() doesn’t have a fill color defined. This causes a quick color flicker in the WordPress admin menu during page load.

How to test the Change

1. Activate the plugin (or keep it active if already).
2. Go to the WordPress admin dashboard.
3. Observe the admin menu icon for the plugin during page load.
4. Without this change, the icon briefly flashes without color (transparent) before WordPress applies the default fill.
5. With this change, the icon color is consistent (#a7aaad) from the very beginning — no flicker should be visible.

Changelog Entry

Changed - menu SVG icon with default color

Credits

Props @lenvan

Checklist:

• [x] I agree to follow this project's Code of Conduct.
• [x] I have updated the documentation accordingly.
• [x] I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• [x] All new and existing tests pass.