firmware(esp-01s): real GoPro Hero 3 status read (was the shutter bug)

Validated against a Hero 3 Silver:
- fetchStatus() now GETs the status endpoint /camera/se (was /bacpac/SH?p=%01,
  which *started recording* every poll), at the correct host 10.5.5.9.
- Read the response from the stream, not getString(): the blob is binary and
  starts with 0x00, which truncated the Arduino String to empty.
- Offsets: recording = byte 29 (confirmed by not-recording vs recording diff),
  battery_raw = byte 19 (drains with charge; calibrate on the hub),
  video_remaining = bytes 25-26 (provisional).
- Default config set to this camera (goprosilver-1 / 10.5.5.9); per-camera
  values can still be overridden at runtime via set_config.

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

firmware/data/esp8266-config.json

@@ -1,6 +1,6 @@
 {
-  "camera_ssid": "GOPRO-BP-",
-  "camera_password": "goprohero",
-  "camera_ip": "10.5.5.1",
+  "camera_ssid": "goprosilver-1",
+  "camera_password": "Bzyeatn421",
+  "camera_ip": "10.5.5.9",
   "poll_interval_sec": 30
 }