feat(pipeline): pass the configured frame rate to each ISO NDI sender

IsoPipeline now hands config.Settings.FrameRate (the exact rational) to the
NdiSender it builds, completing the settings -> sender plumbing. Previously
every output advertised 59.94 regardless of the operator-configured target.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Dragon-ISO.Engine/Pipeline/IsoPipeline.cs

@@ -378,9 +378,10 @@ public sealed class IsoPipeline : IAsyncDisposable
 
         using var receiver = new NdiReceiver(
             interop, config.SourceName, rawWriter, loggerFactory.CreateLogger<NdiReceiver>());
+        var (frameRateN, frameRateD) = config.Settings.FrameRate;
         using var sender = new NdiSender(
             interop, config.OutputName, processedChannel.Reader, loggerFactory.CreateLogger<NdiSender>(),
-            config.OutputGroups);
+            config.OutputGroups, frameRateN, frameRateD);
 
         var processor = new FrameProcessor(
             config.Settings, scaler, new SolidFrameRenderer(),

src/tests/Dragon-ISO.Engine.Tests/Pipeline/IsoPipelineTests.cs

@@ -1,6 +1,7 @@
 using Microsoft.Extensions.Logging.Abstractions;
 using DragonISO.Engine.Domain;
 using DragonISO.Engine.Pipeline;
+using DragonISO.Engine.Tests.Fakes;
 
 namespace DragonISO.Engine.Tests.Pipeline;
 
@@ -76,6 +77,32 @@ public class IsoPipelineTests
         await pipeline.StopAsync();
     }
 
+    [Fact]
+    public async Task ProductionCtor_PassesConfiguredFrameRate_ToSender()
+    {
+        // The operator configures 29.97 in settings; the NDI sender for every ISO
+        // output must be created with that exact rational (30000/1001), not the
+        // hardwired 59.94 default.
+        var interop = new FakeNdiInterop();
+        var config = new IsoPipelineConfig(
+            Guid.NewGuid(),
+            "Teams - Alice",
+            "Alice-ISO",
+            FrameProcessingSettings.Default with { Framerate = TargetFramerate.Fps29_97 });
+        var pipeline = new IsoPipeline(
+            config, interop, new ManagedNearestNeighborFrameScaler(), new FakeFrameClock(),
+            FastBackoff(), NoDelay(), NullLoggerFactory.Instance);
+
+        await pipeline.StartAsync();
+        var deadline = DateTime.UtcNow.AddSeconds(2);
+        while (!interop.SenderFrameRates.ContainsKey("Alice-ISO") && DateTime.UtcNow < deadline)
+            await Task.Delay(10);
+        await pipeline.StopAsync();
+
+        interop.SenderFrameRates.Should().ContainKey("Alice-ISO");
+        interop.SenderFrameRates["Alice-ISO"].Should().Be((30000, 1001));
+    }
+
     [Fact]
     public async Task Supervisor_FailsRepeatedly_TransitionsToError()
     {