Add IMPROVEMENTS.md with design suggestions

[2technology]

Created a markdown document detailing the investigation and providing specific hardware design improvements for the KiCAD schematic, including upgrading the MOSFET to a logic-level version, using a more robust flyback diode, adding I2C pullups, and fixing the gate pulldown placement.

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PR created automatically by Jules for task 7696086215571760711 started by @2technology

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