chore: add unique assets from other branches into dan_branch

Bring hardware/spec content from drho1y-mvp_1 (3d_models, arduino_code, backend_control, kicad, specification) so dan_branch holds the shared union of branch files without rewriting other branch tips.

Co-authored-by: Cursor <cursoragent@cursor.com>

arduino_code/Test/platformio.ini

@@ -0,0 +1,23 @@
+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:upesy_wroom]
+platform = espressif32
+board = upesy_wroom
+framework = arduino
+monitor_speed = 115200
+upload_speed = 921600
+upload_port = /dev/ttyUSB0
+lib_deps = 
+	knolleary/PubSubClient@^2.8
+	janelia-arduino/TMC2209@^9.4.0
+	madhephaestus/ESP32Servo@^3.2.1
+	adafruit/Adafruit PWM Servo Driver Library@^3.0.3
+	pololu/VL53L0X@^1.3.1