Add alternative build method using Docker (Arduino IDE not required)

[rewolt]

This PR introduces a complete Docker-based build workflow for yoRadio, offering an alternative to compiling via the Arduino IDE. This significantly simplifies the build process for users who prefer containerized environments or wish to avoid local installation and configuration of the Arduino IDE, toolchains, and libraries.

Key Changes & Benefits

• Added a comprehensive guide in README.md under a new section, "Alternative build using a docker builder (Arduino IDE not needed)."
• The docker-builder/dockerfile sets up a complete, reproducible build environment.
• Users only need Docker and esptool installed on their host system. The build process is reduced to a few simple terminal commands, making it faster and less error-prone.

Please, check:

• Review the updated README.md section for clarity and accuracy of the build steps.
• Verify the dependencies and steps in the docker-builder/dockerfile (Arduino CLI, ESP32 core, libraries, and patch) are correct.
• Check the logic and error handling in the docker-builder/compile.sh script.

This change should enhance accessibility and reproducibility for all contributors and users.