Replace MicroPython runtime with Pico C + W5500 firmware.

Ship UDP RGB panel firmware (eight WS2812 strips) and drop the ESP32 Wi-Fi/MicroPython stack.

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

.env.example

@@ -0,0 +1,21 @@
+# Copy to .env and adjust. Used by firmware/Makefile.
+# CLI overrides still win: make deploy PANEL_ID=1 NETWORK=dhcp
+#
+# Strip defaults: GP18, 19, 20, 21, 22, 26, 27, 28
+
+PANEL_ID=0
+
+# static | dhcp  (static values below are also DHCP fallback)
+NETWORK=static
+IP=10.1.1.10
+NETMASK=255.255.255.0
+GATEWAY=10.1.1.1
+DNS=10.1.1.1
+
+# Optional (override strip 0 / 1 only):
+# WS2812_PIN=18
+# WS2812_PIN1=19
+# PICO_SDK_PATH=/home/you/pico/pico-sdk
+# JOBS=4
+# SERIAL_PORT=/dev/ttyACM0
+# SERIAL_BAUD=115200