hive-c0re doesn't touch these files anymore (nginx hosts them
directly, see the previous commit) — hive-c0re/swagger-ui-theme/ was
a leftover from the original SWAGGER_UI_OVERWRITE_FOLDER build-hook
design, which this PR moved away from. New location matches the
existing top-level-directory-for-nix-packaged-assets convention
(branding/, claude-plugins/).
Pure rename, no content change: nix/packages/swagger-ui-theme.nix's
three file references updated, everything else picks it up from the
same content hash (nix build .#swagger-ui-theme resolves to the exact
same store path as before the move).
3ef166738c