v0.4.1: browser control (not tested on hardware yet)

ESP-Drone with browser control, v0.4.1. 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

• Fixed in v0.4.1: the phone page connected but never got an answer ("Poor link" and
  "Disconnected" in turn). ESP-IDF 5.5 no longer calls the WebSocket handler after the
  handshake, so the drone never registered the browser. Tested on an E1 Mini.
• 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.
• Flips (experimental, hidden by default): switch them on in the Info dialog of the phone page
  or in the ground station; the drone flies the flip by itself. Needs 2 m of height and room.
  How it works.
• 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

09ac48a1d2bcb0bf26a60b2af7c577df1e9ae63cc7901e9806040a678243e3cc  espdrone-e1-mini-esp32.bin
13c2aaa33fc202b953f943953c10d38b48d19bed7d2febed6c71c26498450851  espdrone-s2-drone-esp32s2.bin
70f1ceccc422eb8b3417228c6a817b1c11c5fcaf1cf9ef95de60074f639b8af4  espdrone-s2-drone-esp32s3.bin