refactor(stores): split dockview store into problem-specific store

- Remove generic dockview store (`src/stores/dockview.tsx`)
- Add problem-specific dockview store (`src/stores/problem-dockview.tsx`)
- Remove submission-related state as it's no longer needed

src/stores/dockview.ts

@@ -1,34 +0,0 @@
-import { create } from "zustand";
-import type { DockviewApi } from "dockview";
-import { createJSONStorage, persist } from "zustand/middleware";
-import type { SubmissionWithTestcaseResult } from "@/types/prisma";
-
-export type DockviewState = {
-  api: DockviewApi | null;
-  submission: SubmissionWithTestcaseResult | null;
-};
-
-export type DockviewActions = {
-  setApi: (api: DockviewApi) => void;
-  setSubmission: (submission: SubmissionWithTestcaseResult) => void;
-};
-
-export type DockviewStore = DockviewState & DockviewActions;
-
-export const useDockviewStore = create<DockviewStore>()(
-  persist(
-    (set) => ({
-      api: null,
-      submission: null,
-      setApi: (api) => set({ api }),
-      setSubmission: (submission) => set({ submission }),
-    }),
-    {
-      name: "zustand:dockview",
-      storage: createJSONStorage(() => localStorage),
-      partialize: (state) => ({
-        submission: state.submission,
-      }),
-    }
-  )
-);

src/stores/problem-dockview.ts

@@ -0,0 +1,20 @@
+import { create } from "zustand";
+import type { DockviewApi } from "dockview";
+
+export type ProblemDockviewState = {
+  api: DockviewApi | null;
+};
+
+export type ProblemDockviewActions = {
+  setApi: (api: DockviewApi) => void;
+};
+
+export type ProblemDockviewStore = ProblemDockviewState &
+  ProblemDockviewActions;
+
+export const useProblemDockviewStore = create<ProblemDockviewStore>()(
+  (set) => ({
+    api: null,
+    setApi: (api) => set({ api }),
+  })
+);