Add HomeMaster to Smart Home and IoT

[isystemsautomation-com-dev]

Hi! Adding HomeMaster to the Smart Home and IoT projects section.

What it is:
HomeMaster is an open-source modular smart home automation platform built around ESP32-based DIN-rail controllers (MiniPLC and MicroPLC) plus a family of expansion modules: relay/digital I/O, AC dimmer, RGBCCT LED, stair lighting, energy meter, RTD/analog inputs, water leak detection, alarm I/O, and OpenTherm gateway. All firmware ships as ready-to-use ESPHome YAML, with native Home Assistant integration and RS-485 Modbus backbone for industrial-grade reliability.

Why ESP-related (per contributing.md):

• All controllers are ESP32-based.
• All firmware is ESPHome (which targets ESP-IDF / Arduino-ESP32).
• Already listed on the official devices.esphome.io directory.

Links / references:

• Website: https://www.home-master.eu
• GitHub (firmware, schematics, manuals): https://github.com/isystemsautomation/homemaster-dev
• Existing ESPHome devices entry: https://devices.esphome.io/devices/homemaster-microplc/ , https://devices.esphome.io/devices/Homemaster-MiniPLC/ , https://devices.esphome.io/devices/Homemaster-OpenthermGateway/

Format checklist:

• HTTPS link, no redirect
• ESP32 explicitly mentioned in description
• Description matches the style of neighboring entries
• No trailing whitespace, ends with period

Thanks for maintaining this list!