feat: implement Redis Streams support with stream checkpoints and update history

- Added Redis Streams operations to the message bus interface and implementation.
- Introduced StreamCheckpoint model to track last processed stream entry per document.
- Implemented UpsertStreamCheckpoint and GetStreamCheckpoint methods in the Postgres store.
- Created document_update_history table for storing update payloads for recovery and replay.
- Developed update persist worker to handle Redis Stream updates and persist them to Postgres.
- Enhanced Docker Compose configuration for Redis with persistence.
- Updated frontend API to support fetching document state with optional share token.
- Added connection stability monitoring in the Yjs document hook.

backend/internal/store/postgres.go

@@ -53,6 +53,15 @@ type Store interface {
 	GetDocumentVersion(ctx context.Context, versionID uuid.UUID) (*models.DocumentVersion, error)
 	GetLatestDocumentVersion(ctx context.Context, documentID uuid.UUID) (*models.DocumentVersion, error)
 
+	// Stream checkpoint operations
+	UpsertStreamCheckpoint(ctx context.Context, documentID uuid.UUID, streamID string, seq int64) error
+	GetStreamCheckpoint(ctx context.Context, documentID uuid.UUID) (*models.StreamCheckpoint, error)
+
+	// Update history (WAL) operations
+	InsertUpdateHistoryBatch(ctx context.Context, entries []UpdateHistoryEntry) error
+	ListUpdateHistoryAfterSeq(ctx context.Context, documentID uuid.UUID, afterSeq int64, limit int) ([]UpdateHistoryEntry, error)
+	DeleteUpdateHistoryUpToSeq(ctx context.Context, documentID uuid.UUID, maxSeq int64) error
+
 	Close() error
 }