feat: implement settings engine with directory picker and aria2 configuration sync

src/store/settingsStore.ts

@@ -0,0 +1,66 @@
+import { create } from 'zustand';
+import { persist, createJSONStorage, StateStorage } from 'zustand/middleware';
+import { LazyStore } from '@tauri-apps/plugin-store';
+
+export const tauriStore = new LazyStore('store.bin');
+
+const tauriStorage: StateStorage = {
+  getItem: async (name: string): Promise<string | null> => {
+    if (name === 'firelink-engine-settings') {
+      try {
+        const data = await tauriStore.get<string>('engine_settings');
+        return data || null;
+      } catch (e) {
+        console.error("Failed to load engine settings from DB", e);
+        return null;
+      }
+    }
+    return null;
+  },
+  setItem: async (name: string, value: string): Promise<void> => {
+    if (name === 'firelink-engine-settings') {
+      try {
+        await tauriStore.set('engine_settings', value);
+        await tauriStore.save();
+      } catch (e) {
+        console.error("Failed to save engine settings to DB", e);
+      }
+    }
+  },
+  removeItem: async (_name: string): Promise<void> => {
+    // no-op for now
+  },
+};
+
+export interface SettingsState {
+  defaultDownloadPath: string;
+  globalSpeedLimit: number;
+  concurrentDownloads: number;
+
+  setDefaultDownloadPath: (path: string) => void;
+  setGlobalSpeedLimit: (limit: number) => void;
+  setConcurrentDownloads: (count: number) => void;
+}
+
+export const useSettingsStore = create<SettingsState>()(
+  persist(
+    (set) => ({
+      defaultDownloadPath: '~/Downloads',
+      globalSpeedLimit: 0,
+      concurrentDownloads: 3,
+
+      setDefaultDownloadPath: (path) => set({ defaultDownloadPath: path }),
+      setGlobalSpeedLimit: (limit) => set({ globalSpeedLimit: limit }),
+      setConcurrentDownloads: (count) => set({ concurrentDownloads: count }),
+    }),
+    {
+      name: 'firelink-engine-settings',
+      storage: createJSONStorage(() => tauriStorage),
+      partialize: (state) => ({
+        defaultDownloadPath: state.defaultDownloadPath,
+        globalSpeedLimit: state.globalSpeedLimit,
+        concurrentDownloads: state.concurrentDownloads,
+      }),
+    }
+  )
+);