Add support for extra themes, other small changes, drop btop

src_files/imports/themes-omarchy-extra/pina/ATTRIBUTION.md

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+# Pina - omarchy-pina-theme
+
+- Author: bjarneo (aka: iamdothash)
+- Upstream repo: https://github.com/bjarneo/omarchy-pina-theme
+
+All files within this `pina` directory are copied or derived from the repo above.
+
+**NOTE:** As of 2025-10-30, no license is currently indicated for this repo/project
+overall. However, there is a brief reference to the MIT license in the
+`pina.nvim/colors/pina.vim` file in its original state, which I have also left in the
+copy/derivative of that file. This said, I wonder if the intent may have been to license
+the whole repo/project under an MIT license, but I hesitate to explicitly add a LICENSE
+file in this theme's directory since no LICENSE file was in the original/upstream repo.
+