The registry espressif32 platform still ships Arduino core 2.0.17, which
lacks ESP32-C6 support. Switch every ESP32 env to the pioarduino fork
(Arduino-ESP32 3.x) via a shared ${common.platform_esp32} variable and
consolidate shared settings into [env].
Rewrite the PWM code for the 3.x LEDC API:
- ledcSetup + ledcAttachPin -> ledcAttach(pin, freq, res)
- ledcDetachPin -> ledcDetach
- ledcWrite now addresses PWM by pin instead of channel index
Adds the esp32-c6-devkitc-1 env; all four ESP32 envs build clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
adebaumann
