hardware: retire dashboard uart and assign oled pins

docs/UART_PROTOCOL.md

@@ -274,3 +274,20 @@ Alternative:
 `status_response.config.temperature_sensors[]` and `status_response.temps[]` include `weather: false`.
 
 `config_temp` may include `weather: true` to mark one configured sensor as the outside/weather sensor. Clients should treat this as optional and default missing values to `false`.
+
+
+## Current communications and GPIO decision
+
+Active dashboard communication is WiFi/HTTP using `/api/v1`.
+
+The old Pico/dashboard UART path is retired from active hardware use. USB Serial remains available for development, debug, and manual configuration from a computer.
+
+Current Cargo ESP32 GPIO plan:
+
+- GPIO 16: Relay 1 trigger output
+- GPIO 17: Relay 2 trigger output
+- GPIO 4: DS18B20 OneWire temperature bus
+- GPIO 34: Ignition sense input
+- GPIO 21: SSD1306 OLED I2C SDA
+- GPIO 22: SSD1306 OLED I2C SCL
+- GPIO 25: OLED setup/status button