The indigo filled square didn't match the in-page Logo component. The nav-bar
logo is a monochrome outlined rounded square + M path, currentColor on the
dark page background.
Favicon now follows the same design: outlined rect + M, stroke adapts:
- light browser tabs → #0A0A0B (near-black)
- dark browser tabs → #FAFAFA
Apple-icon stays as the indigo filled tile — iOS home-screen icons need solid
backgrounds, monochrome outlines disappear there.
9acc2adb0d