Initial commit: plasma DMD driver project

- Design docs: 12 V DC power supply, safety and bring-up, ESP32 interface, BOM
- PSU schematic (schemdraw) and KiCad 10 carrier-board project with HV net classes
- ESP32 PlatformIO firmware skeleton with HV watchdog toggle
- Reference schematic of the Stern 520-5138-00 display PSU

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

firmware/platformio.ini

@@ -0,0 +1,5 @@
+[env:wemos_d1_mini32]
+platform = espressif32
+board = wemos_d1_mini32
+framework = arduino
+monitor_speed = 115200