📦 Created config files with common code

- Created common.nix for various configs
- Created theme.nix for theme related configs
- Moved some code to more logical files
- Moved some standalone files into nix multiline strings, in order to
  inject data

modules/qt.nix

@@ -0,0 +1,11 @@
+{ pkgs, ... }:
+
+{
+  environment.systemPackages = with pkgs.kdePackages; [
+    qtwayland
+    qtsvg
+    qt6ct
+  ];
+
+  qt.enable = true;
+}