Define UART decoder

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

switch_uart_protocol.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "switch_input.h"
+
+bool switch_uart_decode_input_frame(
+    const uint8_t* packet,
+    uint8_t length,
+    SwitchInputState* out_state);