API for change browser's header/address bar color

> Styromaniac · styromaniac@zeroid.bit
> @Nofish: Can you make it so theme-color works in default view?
>
> Styromaniac · styromaniac@zeroid.bit
> https://stackoverflow.com/questions/26960703/how-to-change-the-color-of-header-bar-and-address-bar-in-newest-chrome-version-o

Read the linked Stack Overflow discussion first, then trace the ZeroNet default view to determine where browser page metadata is assembled. Done means theme-color is supported in that view and the browser header or address-bar color changes as requested; no file or test is named, so identify the relevant entry point and verification path before editing.

Written by the indexing model from the issue text.