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>

assets/themes/ristretto/apps/neovim.lua

@@ -0,0 +1,31 @@
+return {
+  {
+    "gthelding/monokai-pro.nvim",
+    config = function()
+      require("monokai-pro").setup({
+        filter = "ristretto",
+        override = function()
+          return {
+            NonText = { fg = "#948a8b" },
+            MiniIconsGrey = { fg = "#948a8b" },
+            MiniIconsRed = { fg = "#fd6883" },
+            MiniIconsBlue = { fg = "#85dacc" },
+            MiniIconsGreen = { fg = "#adda78" },
+            MiniIconsYellow = { fg = "#f9cc6c" },
+            MiniIconsOrange = { fg = "#f38d70" },
+            MiniIconsPurple = { fg = "#a8a9eb" },
+            MiniIconsAzure = { fg = "#a8a9eb" },
+            MiniIconsCyan = { fg = "#85dacc" }, -- same value as MiniIconsBlue for consistency
+          }
+        end,
+      })
+      vim.cmd([[colorscheme monokai-pro]])
+    end,
+  },
+  {
+    "LazyVim/LazyVim",
+    opts = {
+      colorscheme = "monokai-pro",
+    },
+  },
+}