Integrate arduino-cli into Cuyamaca for compiling and flashing Arduino sketches to boards. Use this skill whenever the user wants to add board flashing, integrate arduino-cli, implement the compile and upload workflow, detect connected boards, manage arduino-cli as a child process, or references "phase 5", "arduino-cli", "flash", "compile", "upload sketch", "board detection", or "flashing workflow". Also trigger when the user asks about arduino-cli commands, board FQBN strings, core installation, or the compile-flash pipeline. This skill assumes Phase 4 is complete (code generation, sketch approval, tools.json).