Schematic includes:
- Power section: SS14 reverse protection, AMS1117-3.3 LDO
- RP2040-Zero and OLED module headers
- Trigger output: 74LVC1G17 Schmitt buffer
- Return input: voltage divider, BAT54 clamps, MCP6001 buffer
- Button with pull-up, power LED
BOM updated with correct parts and LCSC numbers.
ASCII schematic reference in hardware/kicad/README.md.