feat: sync ephemeral transient messages

Sync telesrv 570ccf8 (feat(ephemeral): implement Layer 228 transient messages).

Skipped telesrv docs changes per public sync rules; normalized the public appearance seed label.

internal/store/ephemeral.go

@@ -0,0 +1,54 @@
+package store
+
+import (
+	"context"
+	"time"
+
+	"telesrv/internal/domain"
+)
+
+// EphemeralMessageStore is the short-lived authoritative state used for
+// idempotency, callback, edit, delete and report lookups. Implementations must
+// make Create atomic across the message ID and random-ID indexes.
+type EphemeralMessageStore interface {
+	CreateEphemeralMessage(ctx context.Context, message domain.EphemeralMessage) (stored domain.EphemeralMessage, created bool, err error)
+	GetEphemeralMessage(ctx context.Context, peer domain.Peer, id int, now time.Time) (domain.EphemeralMessage, bool, error)
+	EditEphemeralMessage(ctx context.Context, peer domain.Peer, id int, expectedVersion uint64, content domain.EphemeralContent, editDate int, now time.Time) (domain.EphemeralMessage, error)
+	DeleteEphemeralMessage(ctx context.Context, peer domain.Peer, id int, expectedVersion uint64, now time.Time) (domain.EphemeralMessage, bool, error)
+	PruneExpiredEphemeralMessages(ctx context.Context, now time.Time, limit int) (int, error)
+	PutEphemeralCallbackAction(ctx context.Context, action domain.EphemeralCallbackAction) (bool, error)
+	GetEphemeralCallbackAction(ctx context.Context, botUserID, queryID int64, now time.Time) (domain.EphemeralCallbackAction, bool, error)
+}
+
+// EphemeralReportStore is deliberately durable: transient messages disappear
+// after 48 hours, while a submitted abuse report must retain review evidence.
+type EphemeralReportStore interface {
+	CreateEphemeralReport(ctx context.Context, report domain.EphemeralAbuseReport) (created bool, err error)
+}
+
+type EphemeralPushKind string
+
+const (
+	EphemeralPushNew      EphemeralPushKind = "new"
+	EphemeralPushEdit     EphemeralPushKind = "edit"
+	EphemeralPushDelete   EphemeralPushKind = "delete"
+	EphemeralPushCallback EphemeralPushKind = "callback"
+)
+
+// EphemeralPush is a process-to-process online accelerator. It is deliberately
+// not a durable event: Redis Pub/Sub and ready Layer 228 sessions are the only
+// consumers, while EphemeralMessageStore remains the short-lived lookup truth.
+type EphemeralPush struct {
+	SourceID              string
+	Kind                  EphemeralPushKind
+	TargetUserID          int64
+	TargetBusinessAuthKey [8]byte
+	Message               domain.EphemeralMessage
+	Callback              *domain.BotCallbackQuery
+	Date                  int
+}
+
+type EphemeralPushBroker interface {
+	PublishEphemeralPush(ctx context.Context, event EphemeralPush) error
+	SubscribeEphemeralPushes(ctx context.Context, handle func(context.Context, EphemeralPush)) error
+}