Added a Nix Flake and support for running from the Nix Store (#47)

* Added a Nix Flake and support for running from the Nix Store

* Removed variable imports since they're brough in at the top level.

* Removed redundan imports and remove unused files (moved to temp).

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Co-authored-by: Jas Singh <jaskiratpal.singh@outlook.com>

scss/style/bar/systray.scss

@@ -1,5 +1,3 @@
-@import "../colors";
-
 .systray button:not(:first-child) {
   margin-left: 0.75rem;
 }
@@ -7,6 +5,7 @@
 .systray-menu {
   background: $crust;
 }
+
 .systray-menu label {
   font-weight: bold;
   color: $text;