feat(admin): 用户列表新增「调余额」人工充值/扣减入口

- 新接口 POST /api/admin/users/:id/balance（requireAdmin）：事务锁行、扣减不可为负、单次上限 100 万、写 finance_records 并推送站内通知

- 后台用户列表每行新增「调余额」按钮与弹窗（当前余额/方向/金额/备注）

- 新增 admin-balance-adjust 护栏；113 套件/737 用例全绿

server/src/db/repository.ts

@@ -4204,6 +4204,76 @@ export class MysqlRepository {
     return this.getUserById(id);
   }
 
+  /**
+   * 管理后台人工调整钱包余额（运营/测试）：事务内锁行、校验余额、写财务流水。
+   */
+  async adjustUserBalance(
+    id: number,
+    amount: number,
+    direction: 'IN' | 'OUT',
+    reason: string,
+    operator: string
+  ): Promise<any> {
+    const userId = Number(id);
+    const amt = Number(amount);
+    if (!userId || !Number.isFinite(amt) || amt <= 0) {
+      throw new Error('调整金额必须大于 0');
+    }
+    if (amt > 1000000) {
+      throw new Error('单次调整金额不能超过 ¥1,000,000');
+    }
+    const dir: 'IN' | 'OUT' = direction === 'OUT' ? 'OUT' : 'IN';
+    const note = String(reason || '').trim().slice(0, 80);
+
+    const conn = await pool.getConnection();
+    try {
+      await conn.beginTransaction();
+      const [uRows]: any = await conn.query('SELECT id, nickname, balance FROM users WHERE id = ? FOR UPDATE', [userId]);
+      if (!uRows || uRows.length === 0) {
+        throw new Error('用户不存在');
+      }
+      const before = Number(uRows[0].balance) || 0;
+      const delta = dir === 'IN' ? amt : -amt;
+      const after = Number((before + delta).toFixed(2));
+      if (after < 0) {
+        throw new Error(`余额不足：当前余额 ¥${before.toFixed(2)}，无法扣减 ¥${amt.toFixed(2)}`);
+      }
+
+      await conn.query('UPDATE users SET balance = ? WHERE id = ?', [after.toFixed(2), userId]);
+
+      const recId = `fin_admin_${Date.now()}_${Math.floor(100 + Math.random() * 900)}`;
+      const recNo = `ADM${Date.now()}`;
+      await conn.query(`
+        INSERT INTO finance_records (id, record_no, user_id, type, amount, direction, counterparty, related_id, created_at)
+        VALUES (?, ?, ?, ?, ?, ?, ?, ?, NOW())
+      `, [
+        recId,
+        recNo,
+        userId,
+        dir === 'IN' ? '后台余额充值' : '后台余额扣减',
+        amt.toFixed(2),
+        dir,
+        `${operator || '平台运营'}${note ? ` · ${note}` : ''}`,
+        `admin_${Date.now()}`
+      ]);
+
+      await conn.commit();
+      return {
+        userId,
+        nickname: uRows[0].nickname || '',
+        direction: dir,
+        amount: amt.toFixed(2),
+        before: before.toFixed(2),
+        after: after.toFixed(2)
+      };
+    } catch (e) {
+      try { await conn.rollback(); } catch (_) {}
+      throw e;
+    } finally {
+      conn.release();
+    }
+  }
+
   async rechargeUserBalance(id: number, amount: number, bonusAmount: number = 0): Promise<any> {
     if (isNaN(amount) || amount <= 0) {
       throw new Error('充值金额必须大于0');