fix(activity): 参与人昵称/头像回填真实用户，已注销用户明确标注

- getActivities/getActivityById 的 participants 关联 users，返回真实昵称与头像

- 用户已删除时返回「用户已注销」，避免详情页显示搭子_id

- 118 套件/773 用例全绿；线上活动详情已验证真实昵称

server/src/db/repository.ts

@@ -174,7 +174,7 @@ export class MysqlRepository {
           id: p.id,
           activityId: p.activityId,
           userId: p.userId,
-          nickname: p.nickname || '',
+          nickname: p.nickname || '用户已注销',
           avatar: p.avatar || '',
           payAmountCents: p.payAmountCents,
           checkinStatus: Boolean(p.checkinStatus),
@@ -238,7 +238,11 @@ export class MysqlRepository {
     return {
       ...act,
       allowDynamicPrice: Boolean(act.allowDynamicPrice),
-      participants: ptRows.map((p: any) => ({ ...p, checkinStatus: Boolean(p.checkinStatus) })),
+      participants: ptRows.map((p: any) => ({
+        ...p,
+        nickname: p.nickname || '用户已注销',
+        checkinStatus: Boolean(p.checkinStatus),
+      })),
       joinedCount: ptRows.length,
     };
   }

server/tests/activity-list-content.spec.ts

@@ -30,6 +30,13 @@ describe('ActivityListContent（活动大厅真实数据与内容规范）', ()
     expect(page).toContain('creatorNickname');
   });
 
+  it('活动参与者必须返回真实昵称与头像，而不是只显示搭子_id', () => {
+    const repo = fs.readFileSync(path.join(root, 'server', 'src', 'db', 'repository.ts'), 'utf-8');
+    expect(repo).toContain('LEFT JOIN users u ON u.id = p.user_id');
+    expect(repo).toContain('nickname: p.nickname ||');
+    expect(repo).toContain('avatar: p.avatar ||');
+  });
+
   it('页面严禁包含任何系统 Emoji 字符', () => {
     const emojiRegex = /(?:\p{Extended_Pictographic}|\p{Emoji_Presentation}|[\u2600-\u27BF])/u;
     expect(emojiRegex.test(page)).toBe(false);