fix(mcp): use audio-stream instead of direct I2S - fixes fast mp3/voice playback

- old optimization bypassed audio-stream resampler (16k direct -> MCLK 4.096MHz vs 11.29MHz native)
- brick game correct because it used audio_stream path
- now MCP uses audio_stream_open_output/input + read/write matching native logger stack
- falls back to direct I2S only if audio-stream device missing

Tactility/Private/Tactility/mcp/McpSystem.h

@@ -6,6 +6,7 @@
 #include <string>
 #include <vector>
 #include <tactility/device.h>
+#include <tactility/drivers/audio_stream.h>
 
 namespace tt::mcp {
 
@@ -25,6 +26,8 @@ struct McpSystemState {
     
     // Audio device status
     Device* i2sDevice = nullptr;
+    Device* audioStreamDevice = nullptr;
+    AudioStreamHandle audioHandle = nullptr;
     volatile bool audioBusy = false;
     volatile bool audioRunning = false; // Used to abort play/record loop