fix(douyu): 已绑定账号生成二维码不再立即成功, 正常等待扫码换绑

- 后端: get_xpd_bind_qr 生成二维码前记录绑定前状态(before_bound/
  before_role_name); 轮询判断改为 —— 未绑定: 检测到 bind_role=1 成功;
  已绑定(换绑): 角色名变化才算成功, 角色不变继续等待
- 前端: 弹窗保留二维码与角色信息; 轮询期间显示"当前绑定: 原角色",
  换绑成功显示新角色; 确认绑定维持手动(小程序内人工确认)

web/frontend/src/pages/DouyuTasksPage.tsx

@@ -1064,30 +1064,36 @@ export default function DouyuTasksPage({ handbook }: { handbook: HandbookKind })
   const qrRoleName = resultText(qrRoleSourceResult, 'pending_role_name') || resultText(qrRoleSourceResult, 'role_name');
   const qrAreaName = resultText(qrRoleSourceResult, 'pending_area_name') || resultText(qrRoleSourceResult, 'area_name');
   const qrPlatName = resultText(qrRoleSourceResult, 'pending_plat_name') || resultText(qrRoleSourceResult, 'plat_name');
-  const qrCurrentRoleName = qrQueryRoleName
-    || resultText(qrResult, 'current_role_name')
-    || (
-      resultFlag(qrResult, 'is_bound_act')
-        ? resultText(qrResult, 'role_name')
-        : ''
-    )
-    || (qrQueryIsBoundAct ? qrQueryRoleName : '');
-  const qrCurrentAreaName = resultText(qrQueryResult, 'area_name')
-    || resultText(qrResult, 'current_area_name')
-    || (
-      resultFlag(qrResult, 'is_bound_act')
-        ? resultText(qrResult, 'area_name')
-        : ''
-    )
-    || (qrQueryIsBoundAct ? resultText(qrQueryResult, 'area_name') : '');
-  const qrCurrentPlatName = resultText(qrQueryResult, 'plat_name')
-    || resultText(qrResult, 'current_plat_name')
-    || (
-      resultFlag(qrResult, 'is_bound_act')
-        ? resultText(qrResult, 'plat_name')
-        : ''
-    )
-    || (qrQueryIsBoundAct ? resultText(qrQueryResult, 'plat_name') : '');
+  const qrCurrentRoleName = isXpdBindTask
+    ? resultText(qrResult, 'before_role_name')
+    : (qrQueryRoleName
+      || resultText(qrResult, 'current_role_name')
+      || (
+        resultFlag(qrResult, 'is_bound_act')
+          ? resultText(qrResult, 'role_name')
+          : ''
+      )
+      || (qrQueryIsBoundAct ? qrQueryRoleName : ''));
+  const qrCurrentAreaName = isXpdBindTask
+    ? resultText(qrResult, 'before_area_name')
+    : (resultText(qrQueryResult, 'area_name')
+      || resultText(qrResult, 'current_area_name')
+      || (
+        resultFlag(qrResult, 'is_bound_act')
+          ? resultText(qrResult, 'area_name')
+          : ''
+      )
+      || (qrQueryIsBoundAct ? resultText(qrQueryResult, 'area_name') : ''));
+  const qrCurrentPlatName = isXpdBindTask
+    ? resultText(qrResult, 'before_plat_name')
+    : (resultText(qrQueryResult, 'plat_name')
+      || resultText(qrResult, 'current_plat_name')
+      || (
+        resultFlag(qrResult, 'is_bound_act')
+          ? resultText(qrResult, 'plat_name')
+          : ''
+      )
+      || (qrQueryIsBoundAct ? resultText(qrQueryResult, 'plat_name') : ''));
   const qrRoleLine = qrBindReady
     ? [qrPlatName, qrAreaName, qrRoleName].filter(Boolean).join(' - ')
     : '';