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>

flake.nix

@@ -32,7 +32,22 @@
     };
 
     nixosConfigurations = {
+      # Minimal TTY installer ISO (new golden path)
       installerIso = nixpkgs.lib.nixosSystem {
+        specialArgs = { inherit inputs; };
+        modules = [
+          { nixpkgs.hostPlatform = "x86_64-linux"; }
+          "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix"
+          ./hosts/installer-iso.nix
+          {
+            system.stateVersion = "25.11";
+            networking.hostName = "nomarchy-installer";
+          }
+        ];
+      };
+
+      # Graphical installer ISO (legacy, for users who prefer GUI)
+      installerIsoGraphical = nixpkgs.lib.nixosSystem {
         specialArgs = { inherit inputs; };
         modules = [
           { nixpkgs.hostPlatform = "x86_64-linux"; }
@@ -59,6 +74,7 @@
         ];
       };
 
+      # VM for testing graphical installer
       installerVm = nixpkgs.lib.nixosSystem {
         specialArgs = { inherit inputs; };
         modules = [