Move Nix files into a nix directory

Move everything from `config` to the root level.

nix/modules/home-manager/alacritty.nix

@@ -0,0 +1,42 @@
+{
+  lib,
+  pkgs,
+  self,
+  ...
+}:
+let
+  inherit (lib) strings;
+  inherit (strings) toInt;
+
+  theme = import "${self}/nix/lib/theme" { inherit pkgs; };
+in
+{
+  programs.alacritty = {
+    enable = true;
+
+    settings = {
+      env = {
+        TERM = "screen-256color";
+      };
+
+      window.padding = {
+        x = 15;
+        y = 15;
+      };
+
+      font = {
+        size = toInt "${theme.fonts.monospace.size}";
+
+        bold.style = "Regular";
+        normal.family = "${theme.fonts.monospace.name}";
+
+        offset.y = 6;
+        glyph_offset.y = 3;
+      };
+
+      terminal.shell = {
+        program = "zsh";
+      };
+    };
+  };
+}