feat: update Excel template management and export handling

src/utils/filePicker.js

@@ -55,3 +55,23 @@ export async function openJsonFile() {
   if (!handles.length) return null
   return handles[0].getFile()
 }
+
+export async function openExcelFile() {
+  if (!isOpenPickerSupported()) return null
+
+  const handles = await window.showOpenFilePicker({
+    multiple: false,
+    types: [
+      {
+        description: 'Excel 工作簿',
+        accept: {
+          'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet': ['.xlsx'],
+          'application/vnd.ms-excel': ['.xls']
+        }
+      }
+    ]
+  })
+
+  if (!handles.length) return null
+  return handles[0].getFile()
+}