- websocket client on ESP32

- telemetry protocol builder
- server-side message handling
- database migrations
- telemetry persistence

esp32/main/protocol.h

@@ -7,6 +7,19 @@
 extern "C" {
 #endif
 
+int build_telemetry(
+    char* buf,
+    size_t buf_size,
+    uint32_t msg_id,
+    int64_t ts,
+    uint32_t device_id,
+    const char* metric,
+    const char* source,
+    const char* unit,
+    const int* values,
+    size_t count
+);
+
 int build_telemetry_single(
     char* buf,
     size_t buf_size,