net: re-address hub network 10.60.1.0/24 -> 192.168.8.0/24

The project was designed around a 10.60.1.0/24 travel-router network,
but the actual RemoteRig router uses 192.168.8.0/24 (the C6 associates
and gets 192.168.8.x; hub confirmed at 192.168.8.56). Replace the
network prefix everywhere (last octet preserved; GoPro 10.5.5.1 left
alone).

- scripts/setup-pi.sh: static IP 192.168.8.56/24, gateway 192.168.8.1,
  deploy/health command examples updated
- esp32-mqtt-bridge.cpp: default mqtt_broker -> 192.168.8.56
- firmware/data/config.json: broker -> 192.168.8.56 (wifi_password kept
  blank in git; real value flashed to the device only)
- docs (CONTEXT, MQTT_CONTRACT, READMEs, wireframes): gateway/hub/DHCP
  and example IPs re-addressed for consistency

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hardware/README.md

@@ -158,11 +158,11 @@ GoPro Hero 3 ──(AP @ 10.5.5.1)──→ ESP-01S / ESP8266 camera bridge
                                         UART │ (inside case)
                                              │
 Travel Router ──(AP)────────────────────→ ESP32-C3 MQTT bridge
-(10.60.1.1)                                │
+(192.168.8.1)                                │
                                              │
                                         MQTT │
                                              ▼
-                                   Pi Hub (10.60.1.56)
+                                   Pi Hub (192.168.8.56)
 ```
 
 The ESP8266/ESP-01S and GoPro talk over Wi-Fi. The only cable to the GoPro is USB power from the case side USB-A passthrough port.
@@ -175,7 +175,7 @@ The ESP8266/ESP-01S and GoPro talk over Wi-Fi. The only cable to the GoPro is US
 4. Connect the power bank to the case bottom USB-C input; connect the GoPro USB power cable to the case side USB-A passthrough output.
 5. Toggle rocker switch on.
 6. Verify PWR LED, RGB status LED, and OLED status: camera ID, REC state, battery, link, timer.
-7. Monitor from `http://10.60.1.56:8080`.
+7. Monitor from `http://192.168.8.56:8080`.
 
 ## Case Dimensions