refactor: implement component-based architecture for enhanced maintainability

- Reorganize directory structure into core/, features/, and themes/
- Colocate application Nix logic, configs, scripts, and theme overrides
- Implement 'Inversion of Control' for theming: apps now pull theme-specific layouts
- Update flake.nix and shared library paths to match the new structure
- Document the new Feature-Centric architecture in README.md

features/apps/swayosd.nix

@@ -0,0 +1,41 @@
+{ config, pkgs, lib, ... }:
+
+{
+  services.swayosd = {
+    enable = lib.mkDefault true;
+    stylePath = lib.mkDefault "${config.home.homeDirectory}/.config/swayosd/style.css";
+  };
+
+  xdg.configFile."swayosd/style.css".text = lib.mkDefault ''
+    @define-color background-color #${config.colorScheme.palette.base00};
+    @define-color border-color #${config.colorScheme.palette.base0E};
+    @define-color label #${config.colorScheme.palette.base05};
+    @define-color image #${config.colorScheme.palette.base05};
+    @define-color progress #${config.colorScheme.palette.base0B};
+
+    window {
+      border-radius: 0;
+      opacity: 0.97;
+      border: 2px solid @border-color;
+      background-color: @background-color;
+    }
+
+    label {
+      font-family: '${config.nomarchy.fonts.monospace}';
+      font-size: 11pt;
+      color: @label;
+    }
+
+    image {
+      color: @image;
+    }
+
+    progressbar {
+      border-radius: 0;
+    }
+
+    progress {
+      background-color: @progress;
+    }
+  '';
+}