The Build workflow's matrix-of-everything makes it slow and noisy to test a single device profile. Mirrors the build-one workflow already present in OpenIPC/firmware. Takes a full platform name (e.g. hi3518ev200_lite_switcam-hs303-v2) and runs only that build via builder.sh. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>