perf(s7): span-grouped reads — one PDU per contiguous block instead of one per tag

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7DriverFactoryExtensions.cs

@@ -69,6 +69,11 @@ public static class S7DriverFactoryExtensions
             // tags. The driver maps each RawTagEntry's TagConfig blob through S7TagDefinitionFactory
             // at Initialize; the legacy pre-declared DTO tag path (Name/Address → BuildTag) is retired.
             RawTags = dto.RawTags is { Count: > 0 } ? [.. dto.RawTags] : [],
+            // Block-read grouping knobs. Mapped explicitly like every other key on this DTO — the
+            // options object is never deserialised directly — so omitting them here would leave the
+            // documented "-1 disables grouping" escape hatch unreachable from a deployed config.
+            SpanReadMaxGapBytes = dto.SpanReadMaxGapBytes ?? S7DriverOptions.DefaultSpanReadMaxGapBytes,
+            SpanReadMaxSpanBytes = dto.SpanReadMaxSpanBytes ?? S7DriverOptions.DefaultSpanReadMaxSpanBytes,
             Probe = new S7ProbeOptions
             {
                 Enabled = dto.Probe?.Enabled ?? true,
@@ -122,6 +127,11 @@ public static class S7DriverFactoryExtensions
         public List<RawTagEntry>? RawTags { get; init; }
         /// <summary>Gets the probe configuration.</summary>
         public S7ProbeDto? Probe { get; init; }
+        /// <summary>Gets the largest hole the read planner reads through when merging tags into one
+        /// block request; any value below zero disables block-read grouping. Null keeps the default.</summary>
+        public int? SpanReadMaxGapBytes { get; init; }
+        /// <summary>Gets the largest single planned block read in bytes. Null keeps the default.</summary>
+        public int? SpanReadMaxSpanBytes { get; init; }
     }
 
     /// <summary>Data transfer object for S7 probe configuration.</summary>