v0.3.0: browser control (not tested on hardware yet)

ESP-Drone with browser control, v0.3.0. Not tested on real hardware yet:
remove the propellers and work through the bench checklist in
docs/e1-mini.md before the first flight.

Install

In the browser: https://technikweber.github.io/esp-drone/ (Chrome or Edge on a computer,
one click). Other ways, including Espressif's own tools:
docs/flashing.md.

Each file is a complete image for address 0x0:

File	Board	Chip
espdrone-e1-mini-esp32.bin	E1 Mini ("ESP32 Drone" kit)	ESP32
espdrone-s2-drone-esp32s2.bin	Espressif ESP32-S2-Drone	ESP32-S2
espdrone-s2-drone-esp32s3.bin	Espressif ESP32-S2-Drone with ESP32-S3	ESP32-S3

esptool.py --chip esp32 --port /dev/ttyUSB0 --baud 921600 write_flash 0x0 espdrone-e1-mini-esp32.bin

Back up the factory firmware first if you want to go back (read_flash 0 ALL, see the guide).
From the box to the first hover:
docs/getting-started.md.

What's in it

• Browser control over the drone's Wi-Fi with a captive portal: WebSocket, only the newest
  command counts, late commands are dropped, staged failsafe (hold, level out, descend, off).
• Battery protection: forced landing below 3.0 V, no arming below 3.4 V.
• Roll and pitch trim, stored on the drone, and one-tap levelling on the ground.
  Control page in English and German.
• Desktop ground station (esp-drone-groundstation.html below, open it in Chrome or Edge):
  fly with a gamepad (PlayStation, Xbox, Switch Pro and others), live plots of the flight
  controller at 100 Hz, controller gains changeable in flight and stored on the drone, step test,
  motor test for the bench, flight recorder with CSV export. Guide:
  docs/groundstation.md.
• Board support for the E1 Mini (ESP32 DevKit, MPU6500 on SPI, 8520 motors) with controller
  gains from the vendor firmware.
• Based on espressif/esp-drone master@9d5a4f8, built with ESP-IDF 5.5.

SHA-256

91b5a33b819d857fa97876f1123f9483ebdff84d9e9f07c8eab7d069e4b26ac7  espdrone-e1-mini-esp32.bin
8ceb86f6e7172659871119890b5a2b2ac4f1afd4b199ab14bbc3666aad737458  espdrone-s2-drone-esp32s2.bin
34cdba659865428d196b6b2d50aa7bd23c66f88baa600499368f6f6bfa78509f  espdrone-s2-drone-esp32s3.bin