feat: add ESP8266 support + Akaso camera compatibility config

- Unified firmware for ESP32 (dual-STA) and ESP8266 (time-shared STA)
- ESP8266: alternates between GoPro AP and travel router per poll cycle
- PlatformIO dual-target: esp32dev + esp8266dev (d1_mini)
- camera_ip config field for Akaso/non-GoPro cameras
- LittleFS support for ESP8266 (replaces SPIFFS)
- Camera compatibility table (GoPro H3/H4, Akaso)
- LED polarity handled per-platform (ESP8266 active-low)

ESP8266 time-sharing adds ~4s latency per 30s cycle — invisible at poll rate.

firmware/README.md

@@ -1,29 +1,58 @@
-# RemoteRig — ESP32 Camera Node Firmware
+# RemoteRig — ESP32 / ESP8266 Camera Node Firmware
 
-> **Platform:** PlatformIO (esp32dev) | **Framework:** Arduino
+> **Platform:** PlatformIO (esp32dev + esp8266dev) | **Framework:** Arduino
 > **MQTT Contract:** [docs/MQTT_CONTRACT.md](../docs/MQTT_CONTRACT.md)
 > **Hardware:** [hardware/README.md](../hardware/README.md)
 
 ## Quick Start
 
 ```bash
-# Install PlatformIO (if not already)
+# Install PlatformIO
 pip install platformio
 
-# Build
+# Build for ESP32 (recommended — dual-STA)
 cd firmware
-pio run
+pio run -e esp32dev
 
-# Upload to ESP32 (USB connected)
-pio run --target upload
+# Build for ESP8266 D1 Mini (time-shared STA)
+pio run -e esp8266dev
 
-# Upload SPIFFS config (first time only, or after config changes)
-pio run --target uploadfs
+# Upload to board
+pio run -e esp32dev --target upload
+pio run -e esp8266dev --target upload
+
+# Upload SPIFFS/LittleFS config (first time only)
+pio run -e esp32dev --target uploadfs
+pio run -e esp8266dev --target uploadfs
 
 # Serial monitor
 pio device monitor
 ```
 
+## Platform Differences
+
+| Feature | ESP32 | ESP8266 |
+|---------|-------|---------|
+| Wi-Fi | Dual-STA (simultaneous) | Single STA (time-shared) |
+| Poll latency | 0ms (always connected to both) | ~4s per cycle (switch + poll + switch) |
+| Power draw | ~80mA active | ~70mA active |
+| Cost | ~$5 | ~$3 |
+| Build target | `esp32dev` | `esp8266dev` |
+| Filesystem | SPIFFS | LittleFS |
+| LED pin | GPIO 2 (active high) | GPIO 2 / LED_BUILTIN (active low) |
+
+**ESP8266 workflow:** Every 30s, the ESP8266 switches from the travel router to the GoPro AP (~1s), polls the camera (~2s), switches back to the travel router (~1s), then publishes MQTT. This adds ~4s of latency per cycle but is invisible at 30s poll intervals.
+
+## Camera Compatibility
+
+| Camera | IP | Protocol | Status |
+|--------|-----|----------|--------|
+| GoPro Hero 3 | `10.5.5.1` | HTTP GET `/bacpac/SH` | ✅ Full support |
+| GoPro Hero 4 | `10.5.5.1` | HTTP GET `/gp/gpControl` | ⚠️ Different API — needs adaptation |
+| Akaso Brave 4/7/V50 | `192.168.1.1` or `192.168.42.1` | Varies (HTTP or TCP:7878) | 🔬 Needs testing — config `camera_ip` |
+
+For Akaso or other cameras: set `camera_ip` in config.json. The firmware will attempt the GoPro-style HTTP API at that IP. If the camera uses a different protocol, the `fetchCameraStatus()` and `sendCameraCommand()` functions in `main.cpp` need to be adapted.
+
 ## Configuration
 
 The ESP32 stores configuration in SPIFFS (`data/config.json`):
@@ -97,16 +126,6 @@ The ESP32 stores configuration in SPIFFS (`data/config.json`):
 - **Get password:** `GET /bacpac/sd` (no auth, returns plain text)
 - **Status blob:** 60 bytes binary — see `parseStatus()` in main.cpp for field offsets
 
-## ESP8266 Compatibility
-
-To target ESP8266 instead:
-1. Change `platformio.ini`: `board = d1_mini` under `[env:d1_mini]`
-2. Change `WiFi.h` → `ESP8266WiFi.h`
-3. ESP8266 doesn't do true simultaneous STA — use single STA to travel router, HTTP to GoPro via router bridge
-4. SPIFFS → LittleFS on some boards
-
-ESP32 is recommended for dual-STA capability.
-
 ## Troubleshooting
 
 | Symptom | Check |