feat: 新增群组成员数量统计功能并在接口中返回

实现了群组成员数量统计的接口，包含数据库层统计逻辑，在群组详情、设置等接口中返回实时成员数，同时修复了测试用例中参数空格问题。

server/db/adapter.go

@@ -405,6 +405,7 @@ type TenantBusinessAdapter interface {
 	TenantGroupMemberUpsert(t.TenantID, *t.GroupMember) (*t.GroupMember, error)
 	TenantGroupMemberGet(t.TenantID, string, t.Uid) (*t.GroupMember, error)
 	TenantGroupMemberList(t.TenantID, string, t.GroupMemberListOptions) ([]t.GroupMember, string, error)
+	TenantGroupMembersCount(t.TenantID, []string) (map[string]int64, error)
 	TenantGroupMemberUpdate(t.TenantID, string, t.Uid, t.GroupMemberPatch) (*t.GroupMember, error)
 	TenantUsersShareOpenPrivateGroup(t.TenantID, t.Uid, t.Uid) (bool, error)
 	TenantGroupInvitationCreate(t.TenantID, *t.GroupInvitation) (*t.GroupInvitation, error)

server/db/mysql/tenant_groups.go

@@ -394,6 +394,50 @@ func (a *adapter) TenantGroupMemberList(id t.TenantID, topic string, opts t.Grou
 	return items, next, rows.Err()
 }
 
+// TenantGroupMembersCount counts active members for the given topics using the
+// same visibility rules as TenantGroupMemberList: membership active, subscription
+// not deleted, user not deleted. Returns counts keyed by topic; topics with no
+// active members are absent from the map.
+func (a *adapter) TenantGroupMembersCount(id t.TenantID, topics []string) (map[string]int64, error) {
+	if tenantAdp, err := a.routeGroupTenant(id); err != nil {
+		return nil, err
+	} else if tenantAdp != a {
+		return tenantAdp.TenantGroupMembersCount(id, topics)
+	}
+	if len(topics) == 0 {
+		return map[string]int64{}, nil
+	}
+	placeholders := strings.TrimSuffix(strings.Repeat("?,", len(topics)), ",")
+	args := make([]any, 0, len(topics)+3)
+	args = append(args, t.StateDeleted, id, t.GroupMemberStatusActive)
+	for _, topic := range topics {
+		args = append(args, topic)
+	}
+	ctx, cancel := a.getContext()
+	if cancel != nil {
+		defer cancel()
+	}
+	rows, err := a.db.QueryContext(ctx, tenantShardSQL(id, `SELECT gm.topic, COUNT(DISTINCT gm.user_id) FROM im_group_members AS gm
+		JOIN im_subscriptions AS s ON s.tenant_id=gm.tenant_id AND s.topic=gm.topic AND s.userid=gm.user_id AND s.deletedat IS NULL
+		JOIN im_users AS u ON u.tenant_id=gm.tenant_id AND u.id=gm.user_id AND u.state!=?
+		WHERE gm.tenant_id=? AND gm.member_status=? AND gm.topic IN (`+placeholders+`)
+		GROUP BY gm.topic`), args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	counts := make(map[string]int64, len(topics))
+	for rows.Next() {
+		var topic string
+		var count int64
+		if err = rows.Scan(&topic, &count); err != nil {
+			return nil, err
+		}
+		counts[topic] = count
+	}
+	return counts, rows.Err()
+}
+
 func (a *adapter) TenantUsersShareOpenPrivateGroup(id t.TenantID, userID, peerID t.Uid) (bool, error) {
 	if tenantAdp, err := a.routeGroupTenant(id); err != nil {
 		return false, err