remove unused append(_ data: Data) overload from AudioBuffer

Only one append path exists now: append(from:count:), which is what the
IO proc callback uses. The Data-based overload had no callers in source
and added a dead code path to maintain.

Also resolves CoreAudio.AudioBuffer name collision in tests via typealias.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Sources/AudioTeeCore/Core/AudioBuffer.swift

@@ -82,16 +82,6 @@ public class AudioBuffer {
     availableBytes += count
   }
 
-  /// Appends audio data from a Data value. Delegates to the raw pointer
-  /// path; prefer append(from:count:) when you already have a pointer to
-  /// avoid creating a Data object.
-  public func append(_ data: Data) {
-    data.withUnsafeBytes { bytes in
-      guard let baseAddress = bytes.baseAddress else { return }
-      append(from: baseAddress, count: bytes.count)
-    }
-  }
-
   /// Extracts all complete chunks currently available in the buffer.
   public func processChunks() -> [AudioPacket] {
     var packets: [AudioPacket] = []