feat: theme mode support follows system

src/services/states.ts

@@ -1,6 +1,11 @@
 import { atom } from "recoil";
 import { ApiType } from "./types";
 
+export const atomThemeMode = atom<"light" | "dark">({
+  key: "atomThemeMode",
+  default: "light",
+});
+
 export const atomClashPort = atom<number>({
   key: "atomClashPort",
   default: 0,