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

themes/palettes/lumon/apps/swayosd.css

@@ -0,0 +1,44 @@
+@define-color background-color #1b2d40;
+@define-color border-color #304860;
+@define-color label #d6e2ee;
+@define-color image #d6e2ee;
+@define-color progress #6fb8e3;
+@define-color edge-light #f2fcff;
+
+/* Cancel out Nomarchy defaults */
+window:not(:backdrop),
+window:backdrop {
+    border: none;
+    border-width: 0;
+    background-color: transparent;
+    box-shadow: none;
+    padding: 12px;
+}
+
+/* Draw the Lumon OSD shell */
+window:not(:backdrop) #container,
+window:backdrop #container {
+    border: 2px solid alpha(@border-color, 0.92);
+    background-color: alpha(@background-color, 0.95);
+    padding: 12px 16px;
+    background-clip: padding-box;
+}
+
+image,
+label {
+    color: @label;
+}
+
+progressbar {
+    min-height: 8px;
+}
+
+progressbar trough {
+    background: alpha(@border-color, 0.24);
+    box-shadow: inset 0 1px rgba(242, 252, 255, 0.03);
+}
+
+progressbar progress {
+    background: linear-gradient(90deg, @progress, @edge-light);
+    box-shadow: 0 0 10px rgba(111, 184, 227, 0.18);
+}