Instead of fixed 5s/30s retry intervals, implement exponential backoff:
- Initial delay: 1 second
- Max delay: 60 seconds
- Doubles on each failed attempt
- Resets to minimum on successful connection
This prevents hammering a down broker while still reconnecting
quickly when the issue is transient.
Also includes fix for WiFiState/NetworkState enum mismatch in
getWiFiStatus() which was already on main.
- Create INetworkManager interface for network abstraction
- Add EthernetManager for ENC28J60 module using EthernetENC library
- Update WiFiManager to implement INetworkManager interface
- Update MQTTBridge to use INetworkManager* instead of WiFiManager&
- Add heltec_v3_ethernet PlatformIO environment
- Uses HSPI bus (GPIO 19/20/47/48) separate from LoRa SPI
Feature-flagged WiFi/MQTT capability (WITH_MQTT) that bridges
LoRa mesh packets to MQTT topics over TLS (port 443). Includes:
- WiFiManager: connection handling with AP fallback mode
- MQTTBridge: TLS-secured pub/sub with FNV-1a deduplication
- WebConfig: REST API for WiFi/MQTT settings
- Embedded web UI dashboard for configuration
Default broker: meshqt.l.supported.systems:443 (MQTTS)
Build with: pio run -e heltec_v3_mqtt
