Add LoRa sensor network support

- Design LoRa packet protocol with CRC16 validation
- Add protocol header files (lora_protocol.h, lora_packet.h)
- Create battery-powered remote node firmware template
  - Support for DHT22, BME680, DS18B20 sensors
  - Deep sleep for battery conservation
  - Automatic gateway registration
- Add LoRa receive to gateway firmware
  - RadioLib SX1262 integration
  - Node registry for tracking up to 16 nodes
  - HTTP forwarding of received readings
  - ACK responses to remote nodes
- Create comprehensive setup guide with wiring diagrams

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -130,12 +130,78 @@ All configuration in `include/config.h`:
 - [x] Offline buffering when network unavailable
 - [x] Automatic sensor discovery (1-Wire)
 
-### Future (Phase 3)
-- [ ] LoRa receive for remote sensor nodes
-- [ ] Battery-powered remote node firmware
+### Phase 3: LoRa Network (Complete)
+- [x] LoRa packet protocol design (docs/LORA_PROTOCOL.md)
+- [x] Protocol header files (include/lora_protocol.h, include/lora_packet.h)
+- [x] Battery-powered remote node firmware (remote-node/)
+- [x] LoRa receive for gateway (RadioLib SX1262)
+- [x] Gateway LoRa → HTTP forwarding
+- [x] Automatic node registration and ACK responses
+
+### Future
 - [ ] Sensor agreement monitoring
 - [ ] Flash storage for offline buffer persistence
 
+## Remote Sensor Nodes
+
+Battery-powered sensor nodes in `remote-node/` that transmit to the gateway via LoRa.
+
+### Build & Upload
+```bash
+cd remote-node
+
+# DHT22 variant (ambient temp/humidity)
+pio run -e heltec_v3_dht22 --target upload
+
+# BME680 variant (temp/humidity/pressure/VOC)
+pio run -e heltec_v3_bme680 --target upload
+```
+
+### Configuration
+Edit `remote-node/include/config.h`:
+- `NODE_ID` - Unique ID or 0xFFFF for auto-assign
+- `NODE_NAME` - Human-readable name (8 chars max)
+- `REPORT_INTERVAL_SEC` - How often to transmit (default 60s)
+
+### Power Consumption
+- Deep sleep: ~10 μA
+- Average @ 60s interval: ~1 mA
+- 1000mAh LiPo battery life: ~1 month
+
+## LoRa Protocol
+
+The gateway will receive data from remote sensor nodes via LoRa 915MHz. Full specification in `docs/LORA_PROTOCOL.md`.
+
+### Key Files
+| File | Purpose |
+|------|---------|
+| `docs/LORA_PROTOCOL.md` | Full protocol specification |
+| `include/lora_protocol.h` | Constants, types, CRC functions |
+| `include/lora_packet.h` | Packet builder/parser helpers |
+
+### Supported Sensors
+| Type | Code | Payload Size | Data |
+|------|------|--------------|------|
+| DHT22 | 0x01 | 7 bytes | Temp, Humidity, Battery, RSSI |
+| BME680 | 0x02 | 12 bytes | Temp, Humidity, Pressure, Gas, IAQ |
+| DS18B20 | 0x03 | 5 bytes | Temp (high precision), Battery, RSSI |
+
+### Node ID Ranges
+| Range | Purpose |
+|-------|---------|
+| 0x0001-0x00FF | Tank sensors |
+| 0x0100-0x01FF | Ambient sensors (DHT22) |
+| 0x0200-0x02FF | Environmental (BME680) |
+| 0xFFFF | Auto-assign request |
+
+## Documentation
+
+| Document | Purpose |
+|----------|---------|
+| `docs/SETUP_GUIDE.md` | Complete setup guide with wiring diagrams |
+| `docs/LORA_PROTOCOL.md` | LoRa packet format specification |
+| `remote-node/README.md` | Remote node firmware guide |
+
 ## Related Projects
 
 - **ZNET Web**: `~/Nextcloud/Dev/znet-web` - Backend receives temperature data
@@ -151,3 +217,6 @@ All configuration in `include/config.h`:
 | Date | Version | Change |
 |------|---------|--------|
 | 2026-01-24 | 1.0.0 | Initial implementation |
+| 2026-01-24 | 1.1.0 | LoRa protocol design, header files |
+| 2026-01-24 | 1.2.0 | Remote node firmware template (DHT22, BME680, DS18B20) |
+| 2026-01-24 | 1.3.0 | Gateway LoRa receive, node registry, HTTP forwarding |