channels: give kicked/banned/promoted/transferred users a real qts so their client applies it

updateChannelParticipant carries the account's qts per the MTProto spec, but
the server always sent Qts: 0, so real clients silently discarded it as a
stale duplicate -- the banned/kicked user's channel never vanished locally
and no correct "removed by admin" message showed, even though the update was
delivered successfully at the transport layer.

Add a durable per-device qts queue (channel_participant_event_queue) sharing
its qts number space with the existing secret-chat queue (one qts sequence
per device, per spec), and use it to stamp a correct, monotonically
increasing qts on the update for every device of the affected user -- for
channel bans/kicks, admin promotion/demotion, and ownership transfer. A
device offline when it happened can now recover the event via
updates.getDifference instead of missing it permanently.

internal/domain/channel_participant_queue.go

@@ -0,0 +1,19 @@
+package domain
+
+// DeviceChannelParticipantEvent is a durable, per-device queued entry recording
+// that the receiving account's participant status in a channel changed
+// (kick/ban/promote/demote/ownership transfer). It rides the same qts sequence
+// as SecretChatMessage (one counter per device, shared with secret chats per
+// the MTProto spec for updateChannelParticipant), so a device that misses the
+// live push can recover the event via updates.getDifference instead of never
+// learning it was removed.
+type DeviceChannelParticipantEvent struct {
+	ReceiverAuthKeyID int64
+	ReceiverUserID    int64
+	Qts               int
+	ChannelID         int64
+	ActorUserID       int64
+	Date              int
+	Previous          ChannelMember
+	Participant       ChannelMember
+}