feat: add stylix theme

Break Changes:
- May need reconfigure fcitx5 input method

home/user/internationalisation.nix

@@ -0,0 +1,59 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+let
+  addons = with pkgs; [
+    fcitx5-gtk
+    fcitx5-mozc # Japanese
+    fcitx5-chinese-addons
+    fcitx5-rime # Bopomofo
+    rime-data
+  ];
+
+in
+{
+  i18n = {
+    inputMethod = {
+      enable = true;
+      type = "fcitx5";
+      fcitx5 = {
+        inherit addons;
+        waylandFrontend = true;
+
+        settings = {
+          addons.classicui.globalSection =
+            let
+              font = "Noto Sans CJK TC ${toString config.stylix.fonts.sizes.popups}";
+            in
+            {
+              Font = lib.mkForce font;
+              MenuFont = lib.mkForce font;
+              TrayFont = lib.mkForce font;
+            };
+        };
+      };
+    };
+  };
+
+  systemd.user.services.fcitx5 = {
+    Unit = {
+      WantedBy = [ "graphical-session.target" ];
+      PartOf = [ "graphical-session.target" ];
+      Description = "Fcitx5 Input Method";
+    };
+    Service = {
+      Type = "simple";
+      Restart = "always";
+      RestartSec = 2;
+      ExecStart = "${pkgs.fcitx5}/bin/fcitx5";
+      Environment = [
+        "GTK_IM_MODULE="
+        "XMODIFIERS=@im=fcitx"
+        "QT_IM_MODULE=fcitx"
+      ];
+    };
+  };
+}