perf(db): 高频查询补索引 + 大列表加合理上限（避免全表下发）

- 启动建表后幂等补索引：orders/finance_records/users/reports/companions/payment_intents/payment_refunds 等高频查询列

- 管理端订单/财务流水/用户列表 LIMIT 500，友圈/评价列表 LIMIT 200，防止无界查询

- expert_services 懒建表后补 expert_id 索引

- 新增回归护栏 list-pagination-index.spec.ts（84 套件/625 用例全绿）

server/src/db/repository.ts

@@ -1325,6 +1325,7 @@ export class MysqlRepository {
         created_at as createdAt
       FROM orders
       ORDER BY created_at DESC
+      LIMIT 500
     `);
     return rows;
   }
@@ -1367,6 +1368,7 @@ export class MysqlRepository {
          OR claimed_by = ?
          OR companion_name IN (SELECT name FROM companions WHERE user_id = ? OR id = ?)
       ORDER BY created_at DESC
+      LIMIT 500
     `, [uid, uid, uid, uid, uid]);
     return rows;
   }
@@ -3102,6 +3104,7 @@ export class MysqlRepository {
         created_at as createdAt
       FROM finance_records
       ORDER BY created_at DESC
+      LIMIT 500
     `);
     return rows;
   }
@@ -3508,7 +3511,7 @@ export class MysqlRepository {
       sql += ' AND status = ?';
       params.push(filter.status);
     }
-    sql += ' ORDER BY id ASC';
+    sql += ' ORDER BY id ASC LIMIT 500';
     const [rows]: any = await pool.query(sql, params);
     return rows;
   }
@@ -4286,7 +4289,7 @@ export class MysqlRepository {
     if (where.length > 0) {
       sql += ' WHERE ' + where.join(' AND ');
     }
-    sql += ' ORDER BY is_top DESC, created_at DESC';
+    sql += ' ORDER BY is_top DESC, created_at DESC LIMIT 200';
 
     const [rows]: any = await pool.query(sql, params);
     return rows.map((r: any) => {
@@ -4597,7 +4600,7 @@ export class MysqlRepository {
     if (where.length > 0) {
       sql += ' WHERE ' + where.join(' AND ');
     }
-    sql += ' ORDER BY created_at DESC';
+    sql += ' ORDER BY created_at DESC LIMIT 200';
 
     const [rows]: any = await pool.query(sql, params);
     return rows.map((r: any) => {
@@ -4911,6 +4914,11 @@ export class MysqlRepository {
           created_at DATETIME DEFAULT CURRENT_TIMESTAMP
         )
       `);
+      try {
+        await pool.query('ALTER TABLE expert_services ADD INDEX idx_srv_expert (expert_id)');
+      } catch (_) {
+        // 索引已存在：忽略
+      }
       const [rows]: any = await pool.query('SELECT * FROM expert_services WHERE expert_id = ? ORDER BY created_at ASC', [expertId]);
       if (rows && rows.length > 0) {
         return rows.map((r: any) => ({