- websocket client on ESP32

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

db/migrations/V1__init_protocol.sql

@@ -0,0 +1,20 @@
+CREATE TABLE devices (
+    id BIGINT PRIMARY KEY,
+    is_enabled BOOLEAN NOT NULL DEFAULT TRUE,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE TABLE telemetry (
+    id BIGINT AUTO_INCREMENT PRIMARY KEY,
+    device_id BIGINT NOT NULL,
+    ts BIGINT NOT NULL,
+    metric VARCHAR(32) NOT NULL,
+    source VARCHAR(64) NOT NULL,
+    unit VARCHAR(16) NOT NULL,
+    payload JSON NOT NULL,
+    processed BOOLEAN NOT NULL DEFAULT FALSE,
+
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    FOREIGN KEY (device_id) REFERENCES devices(id)
+);