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>

firmware/timer.c

@@ -0,0 +1,21 @@
+#include "timer.h"
+
+static struct repeating_timer g_timer;
+static void (*g_callback)(void);
+
+void wizchip_1ms_timer_initialize(void (*callback)(void)) {
+    g_callback = callback;
+    add_repeating_timer_us(-1000, wizchip_1ms_timer_callback, NULL, &g_timer);
+}
+
+bool wizchip_1ms_timer_callback(struct repeating_timer *t) {
+    (void)t;
+    if (g_callback != NULL) {
+        g_callback();
+    }
+    return true;
+}
+
+void wizchip_delay_ms(uint32_t ms) {
+    sleep_ms(ms);
+}