Initial design: ESP32-S3 presence sensor with camera, mmWave, PIR, temp/humidity, light

- KiCad schematic and PCB layout (45x35mm board)
- Full BOM with JLCPCB part numbers
- ESPHome firmware configuration
- 3D-printable wall-mount enclosure (OpenSCAD + STL)
- Pin mapping and power budget documentation

enclosure/lid_only.scad

@@ -0,0 +1,2 @@
+use <enclosure.scad>;
+lid();