feat(approval): 文件选择失败时提示完整错误信息

8 张单据表单页原来把 chooseFile/chooseMessageFile/chooseImage 的 fail
吞成 () => undefined，手机上点上传附件没反应时无从判断。改为统一的
chooseFail：优先弹平台 errMsg，缺省时序列化整个 fail 入参。

src/packageApproval/pages/form-coordination.vue

@@ -333,6 +333,18 @@ async function submit() {
   });
 }
 
+/** 文件选择失败时把平台返回的完整错误信息提示出来，便于定位机型/平台限制 */
+function chooseFail(res: any) {
+  let detail = '';
+  try {
+    detail =
+      res && typeof res.errMsg === 'string' ? res.errMsg : JSON.stringify(res);
+  } catch (error) {
+    detail = String(res);
+  }
+  showError('选择文件失败：' + (detail || '未知错误'), null);
+}
+
 function chooseAttachment() {
   if (attachments.value.length >= 9) {
     showError('每单最多上传9张附件', null);
@@ -344,7 +356,7 @@ function chooseAttachment() {
     count: remaining,
     extension: ['.jpg', '.jpeg', '.png', '.pdf', '.doc', '.docx', '.xls', '.xlsx'],
     success: (result: any) => uploadFiles(result.tempFiles || []),
-    fail: () => undefined
+    fail: chooseFail
   });
   // #endif
   // #ifdef MP-WEIXIN
@@ -352,7 +364,7 @@ function chooseAttachment() {
     count: remaining,
     type: 'file',
     success: (result: any) => uploadFiles(result.tempFiles || []),
-    fail: () => undefined
+    fail: chooseFail
   });
   // #endif
   // #ifdef APP-PLUS
@@ -364,7 +376,7 @@ function chooseAttachment() {
       (result.tempFilePaths || []).forEach((path: string) =>
         uploadFiles([{ path, name: path.split('/').pop() || '附件' }])
       ),
-    fail: () => undefined
+    fail: chooseFail
   });
   // #endif
 }