chore: checkpoint app work before firmware sync

Apps/PipecatVoice/main/Source/voice_protocol.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define PV_PROTOCOL_VERSION 1
+#define PV_PCM_CHUNK_MAX 16384U
+#define PV_DOWNSTREAM_MAX 65536U
+
+typedef enum {
+    PV_CONNECTING,
+    PV_STREAMING,
+    PV_RECONNECTING,
+    PV_FAILED,
+} PvState;
+
+typedef struct {
+    char host[64];
+    char path[96];
+    uint16_t port;
+} PvEndpoint;
+
+bool pv_parse_endpoint(const char* url, PvEndpoint* endpoint);
+bool pv_make_start_json(char* out, size_t out_size, const char* session_id, const char* device_id);
+bool pv_valid_pcm_chunk(size_t bytes);
+bool pv_valid_downstream_audio(const char* format, int sample_rate, int channels, int sample_width, size_t byte_length);
+bool pv_binary_matches_metadata(size_t expected_bytes, size_t received_bytes);
+uint32_t pv_retry_delay_seconds(unsigned attempt);
+PvState pv_disconnect_state(bool endpoint_valid);
+const char* pv_state_label(PvState state);