Server: collect tombstones past their retention, compact superseded change entries, and refuse cursors from before a collection

src/DodoSSH.Infrastructure/Migrations/DodoDbContextModelSnapshot.cs

@@ -750,6 +750,10 @@ namespace DodoSSH.Infrastructure.Migrations
                         .HasColumnType("boolean")
                         .HasColumnName("rekey_required");
 
+                    b.Property<long>("SyncHorizon")
+                        .HasColumnType("bigint")
+                        .HasColumnName("sync_horizon");
+
                     b.Property<Guid?>("TeamId")
                         .HasColumnType("uuid")
                         .HasColumnName("team_id");