ESP32 capacitive-touch: add 4 missing circuit diagrams #114

ESP32 capacitive-touch lesson — add missing circuit diagrams

esp32/capacitive-touch.md is published but references 4 image files that aren't in the repo yet (surfaced by the new html-proofer link-check gate). The <img> alt text is already written; only the asset files are missing:

• esp32/assets/images/AdafruitESP32S3FeatherPinDiagram.png (L146 — Feather pin diagram highlighting touch pins)
• esp32/assets/images/ESP32S3_TouchRead_CircuitDiagram_Fritzing.png (L213)
• esp32/assets/images/ESP32S3_TouchLED_CircuitDiagram_Fritzing.png (L314)
• esp32/assets/images/ESP32S3_TouchPiano_CircuitDiagram_Fritzing.png (L585)

Part of the in-progress ESP32 lessons (diagrams/videos still being authored). Until these land, esp32/capacitive-touch.html is on the html-proofer ignore list in .github/workflows/content-lint.yml — remove it from that ignore list once the files are committed so the gate protects the page.

Part of V2.0.