feat(family): 恢复退出切换接口 switch-back-verify（带密码校验）

cfc-backend/src/main/java/com/etotem/cfc/controller/family/FamilyUserController.java

@@ -131,12 +131,22 @@ public class FamilyUserController {
         return Result.error(410, "该接口已废弃，请使用 /api/family/member/switch");
     }
 
-    @Operation(summary = "带密码校验切换回家长视角（已废弃，使用 /api/family/member/switch）")
-    @Deprecated
+    @Operation(summary = "带密码校验退出成员切换（返回原用户身份）")
     @PostMapping("/switch-back-verify")
     public Result<Boolean> switchBackVerify(@RequestAttribute("userId") Long userId,
         @RequestBody Map<String, String> body) {
-        return Result.error(410, "该接口已废弃，请使用 /api/family/member/switch");
+        if (userId == null) {
+            return Result.error("请先登录");
+        }
+        String password = body != null ? body.get("password") : null;
+        if (password == null || password.isEmpty()) {
+            return Result.error("请输入密码");
+        }
+        boolean valid = userService.verifyPassword(userId, password);
+        if (!valid) {
+            return Result.error("密码错误");
+        }
+        return Result.success(true);
     }
 
     @Operation(summary = "创建孩子")