feat(store): add problem editor state management with zustand

src/store/useProblemEditorStore.ts

@@ -0,0 +1,26 @@
+import { create } from "zustand";
+import { EditorLanguage } from "@prisma/client";
+import { createJSONStorage, persist } from "zustand/middleware";
+import { DEFAULT_EDITOR_LANGUAGE } from "@/config/editor-language";
+
+/**
+ * State management for problem editor settings.
+ */
+interface ProblemEditorState {
+  globalEditorLanguage: EditorLanguage;
+  setGlobalEditorLanguage: (language: EditorLanguage) => void;
+}
+
+export const useProblemEditorStore = create<ProblemEditorState>()(
+  persist(
+    (set) => ({
+      globalEditorLanguage: DEFAULT_EDITOR_LANGUAGE,
+      setGlobalEditorLanguage: (language) => set({ globalEditorLanguage: language }),
+    }),
+    {
+      name: "problem-editor",
+      storage: createJSONStorage(() => localStorage),
+      partialize: (state) => ({ globalEditorLanguage: state.globalEditorLanguage }),
+    }
+  )
+);