swaits
be449ac62b
Reverts the removal of heltec_v3 — it's a major board. Xtensa builds use the esp toolchain (+esp via espup); check-all gracefully skips boards whose toolchain isn't installed. Build artifacts now land in firmware/ with readable names like lora-dongle-rak_4631-release.elf instead of being buried in target/. DESIGN.md updated with "support all common boards" principle (#10) and corrected toolchain policy (#11).