feat(sdk): add OutputFormat property with default implementation (3.3.1)

Add optional OutputFormat property to IAudioPlayer and IAudioPipeline
interfaces with default implementation returning null. This is a
non-breaking change - existing implementations continue to work.

- IAudioPlayer.OutputFormat: exposes format sent to output device
- IAudioPipeline.OutputFormat: complements CurrentFormat (incoming)
- Remove emoji from clock sync log message

Note: Never use emojis in log messages - they cause encoding issues
and display problems in various logging backends.

Author: chrisuthe

src/Sendspin.SDK/Audio/IAudioPipeline.cs

@@ -44,7 +44,7 @@ public interface IAudioPipeline : IAsyncDisposable
     /// This value is available after the pipeline has started playing.
     /// </para>
     /// </remarks>
-    AudioFormat? OutputFormat { get; }
+    AudioFormat? OutputFormat => null;
 
     /// <summary>
     /// Gets the detected audio output latency in milliseconds.

src/Sendspin.SDK/Audio/IAudioPlayer.cs

@@ -50,7 +50,7 @@ public interface IAudioPlayer : IAsyncDisposable
     /// format conversion is applied by the audio subsystem.
     /// </para>
     /// </remarks>
-    AudioFormat? OutputFormat { get; }
+    AudioFormat? OutputFormat => null;
 
     /// <summary>
     /// Initializes the audio output with the specified format.

src/Sendspin.SDK/Sendspin.SDK.csproj

@@ -8,7 +8,7 @@
 
     <!-- NuGet Package Metadata -->
     <PackageId>Sendspin.SDK</PackageId>
-    <Version>4.0.0</Version>
+    <Version>3.3.1</Version>
     <Authors>Sendspin Contributors</Authors>
     <Company>Sendspin</Company>
     <Product>Sendspin SDK</Product>
@@ -20,19 +20,14 @@
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <PackageReleaseNotes>
-v4.0.0 - Breaking Changes:
-- BREAKING: IAudioPlayer interface now requires OutputFormat property
-  - Returns the audio format being sent to the output device
-  - Available after InitializeAsync() completes
-  - Existing implementations must add: AudioFormat? OutputFormat { get; }
-- BREAKING: IAudioPipeline interface now requires OutputFormat property
-  - Returns the format being written to the audio output device
-  - Complements CurrentFormat (incoming) with output format info
-
-Migration Guide:
-- Add to your IAudioPlayer implementation:
-  public AudioFormat? OutputFormat => _format; // or your format field
-- If you only use WasapiAudioPlayer (most users), no changes needed
+v3.3.1:
+New Features:
+- IAudioPlayer.OutputFormat: Optional property exposing the audio format sent to output device
+  - Default implementation returns null (non-breaking)
+  - Override in your implementation to expose actual output format
+- IAudioPipeline.OutputFormat: Optional property for output format (complements CurrentFormat)
+  - Default implementation returns null (non-breaking)
+  - Useful for debugging format conversions in the pipeline
 
 v3.3.0:
 New Features:

src/Sendspin.SDK/Synchronization/KalmanClockSynchronizer.cs

@@ -337,7 +337,7 @@ public void ProcessMeasurement(long t1, long t2, long t3, long t4)
             {
                 _driftReliableLogged = true;
                 _logger?.LogInformation(
-                    "🎯 Drift is now reliable! drift={Drift:F2}μs/s (±{Uncertainty:F1}μs/s), " +
+                    "Drift is now reliable: drift={Drift:F2}μs/s (±{Uncertainty:F1}μs/s), " +
                     "offset={Offset:F0}μs, measurements={Count}. " +
                     "Future timestamps will include drift compensation.",
                     _drift,