feat: account management overhaul + 7 issue resolutions (#147)

- Add smart JSON export/import with schema validation and deduplication
- Add per-account proxy configurations (Issue #79)
- Add advanced account sorting engine (Issues #126 & #99)
- Add compact horizontal layout, AI credits, inline model visibility (Issues #145 & #134)
- Add desktop push notifications for low quota (Issue #53)
- Fix Arch Linux AUR process detection bug (Issue #117)
- Default theme set to Dark Mode (it's better)
- UI Polishing: Improved sort dropdown and symmetrical dialog layouts
- Dev Mode: Resolved port conflicts and single-instance locks
- Updated README and README.zh-CN with new features

src/hooks/useCloudAccounts.ts

@@ -4,6 +4,7 @@ import {
   addGoogleAccount,
   deleteCloudAccount,
   refreshAccountQuota,
+  setAccountProxy,
 } from '@/actions/cloud';
 import { CloudAccount } from '@/types/cloudAccount';
 
@@ -120,3 +121,41 @@ export function useSyncLocalAccount() {
 
 import { startAuthFlow } from '@/actions/cloud';
 export { startAuthFlow };
+
+export function useSetAccountProxy() {
+  const queryClient = useQueryClient();
+  return useMutation({
+    mutationFn: setAccountProxy,
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.cloudAccounts });
+    },
+    onError: (error: any) => {
+      console.error('[Mutation] setAccountProxy failed:', error);
+    },
+  });
+}
+
+import { exportCloudAccounts, importCloudAccounts } from '@/actions/cloud';
+
+export function useExportCloudAccounts() {
+  return useMutation<string, Error, { stripTokens?: boolean }>({
+    mutationFn: exportCloudAccounts,
+  });
+}
+
+export function useImportCloudAccounts() {
+  const queryClient = useQueryClient();
+  return useMutation<
+    { imported: number; skipped: number; updated: number; errors: string[] },
+    Error,
+    { jsonContent: string; strategy?: 'merge' | 'overwrite' | 'skip-existing' }
+  >({
+    mutationFn: importCloudAccounts,
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.cloudAccounts });
+    },
+    onError: (error: any) => {
+      console.error('[Mutation] importCloudAccounts failed:', error);
+    },
+  });
+}