refactor: major architectural restructure for theme-centric organization

Theme System:
- Move all theme app configs to apps/ subdirectory (20 themes)
- Add theme-loader.nix for dynamic theme config deployment
- Simplify stylix.nix to focus on base theming only

Override System:
- Add overrides.nix for file-based config overrides
- Add behavior-configs.nix for non-visual configuration
- Split hypr/nomarchy.conf into behavior vs visual sections

Module Improvements:
- Add lib.mkDefault to all customizable settings
- Add modules/lib/ with shared utilities and state schema
- Update all home and system modules for downstream overridability

Installer:
- New minimal TTY installer (installer/install.sh)
- Golden path: BTRFS + LUKS2 (disko-golden.nix)
- New installer-iso.nix for TTY-only installation
- Keep graphical installer as installerIsoGraphical option

Cleanup:
- Remove obsolete install.sh, disko-ext4.nix, install-nomarchy.sh
- Update live-iso.nix references
- Add .claude/ to .gitignore for local IDE settings

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

modules/system/plymouth.nix

@@ -1,4 +1,4 @@
-{ config, pkgs, ... }:
+{ config, pkgs, lib, ... }:
 
 let
   nomarchy-plymouth = pkgs.stdenv.mkDerivation {
@@ -16,15 +16,15 @@ let
   };
 in
 {
-  boot.initrd.systemd.enable = true;
-  boot.initrd.verbose = false;
-  console.earlySetup = true;
-  boot.consoleLogLevel = 0;
+  boot.initrd.systemd.enable = lib.mkDefault true;
+  boot.initrd.verbose = lib.mkDefault false;
+  console.earlySetup = lib.mkDefault true;
+  boot.consoleLogLevel = lib.mkDefault 0;
   boot.plymouth = {
-    enable = true;
-    themePackages = [ nomarchy-plymouth ];
-    theme = "nomarchy";
+    enable = lib.mkDefault true;
+    themePackages = lib.mkDefault [ nomarchy-plymouth ];
+    theme = lib.mkDefault "nomarchy";
   };
 
-  boot.kernelParams = [ "quiet" "splash" "loglevel=3" "rd.systemd.show_status=false" "rd.udev.log_level=3" "udev.log_priority=3" "boot.shell_on_fail" ];
+  boot.kernelParams = lib.mkDefault [ "quiet" "splash" "loglevel=3" "rd.systemd.show_status=false" "rd.udev.log_level=3" "udev.log_priority=3" "boot.shell_on_fail" ];
 }