moved some repeated code

src/useAppStore.js

@@ -0,0 +1,47 @@
+import { create } from 'zustand';
+
+const useAppStore = create((set) => ({
+  captchaResponse: '',
+  setCaptchaResponse: (response) => set({ captchaResponse: response }),
+
+  bodyStyle: JSON.parse(localStorage.getItem('bodyStyle')) || {
+    background: '#ffe url(/assets/fade.png) top repeat-x',
+    color: 'maroon',
+    fontFamily: 'Helvetica, Arial, sans-serif',
+  },
+  setBodyStyle: (bodyStyle) => {
+    localStorage.setItem('bodyStyle', JSON.stringify(bodyStyle));
+    set(() => ({ bodyStyle }));
+  },
+
+  defaultSubplebbits: [],
+  setDefaultSubplebbits: (subplebbits) => set({ defaultSubplebbits: subplebbits }),
+
+  isSettingsOpen: false,
+  setIsSettingsOpen: (isOpen) => set({ isSettingsOpen: isOpen }),
+  
+  selectedAddress: '',
+  setSelectedAddress: (address) => set({ selectedAddress: address }),
+  
+  
+  selectedStyle: localStorage.getItem('selectedStyle') || 'Yotsuba',
+  setSelectedStyle: (style) => {
+    localStorage.setItem('selectedStyle', style);
+    set({ selectedStyle: style });
+  },
+  
+  selectedThread: '',
+  setSelectedThread: (thread) => set({ selectedThread: thread }),
+
+  selectedTitle: '',
+  setSelectedTitle: (title) => set({ selectedTitle: title }),
+
+  showPostForm: false,
+  setShowPostForm: (show) => set({ showPostForm: show }),
+
+  showPostFormLink: true,
+  setShowPostFormLink: (show) => set({ showPostFormLink: show }),
+
+}));
+
+export default useAppStore;