Add ArtNetDMX Pico W firmware with dual DMX and docs.

Art-Net to two RS-485 outputs over Wi-Fi (AP or STA with SoftAP fallback), web UI, mDNS, and QLC+/ArtPoll notes for unicast on STA.

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

src/main.c

@@ -0,0 +1,89 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "pico/stdlib.h"
+#include "pico/stdio_usb.h"
+#include "pico/cyw43_arch.h"
+#include "hardware/pio.h"
+
+#include "board.h"
+#include "config.h"
+#include "channels.h"
+#include "dmx_out.h"
+#include "artnet.h"
+#include "wifi_mgr.h"
+#include "http_server.h"
+
+static dmx_out_t g_dmx[BOARD_NUM_UNIVERSES];
+static uint8_t g_frames[BOARD_NUM_UNIVERSES][BOARD_DMX_FRAME_LEN];
+
+static bool dmx_timer_cb(repeating_timer_t *rt) {
+    (void)rt;
+    for (unsigned u = 0; u < BOARD_NUM_UNIVERSES; u++) {
+        if (dmx_out_busy(&g_dmx[u])) {
+            continue;
+        }
+        channels_build_frame(u, g_frames[u]);
+        dmx_out_write(&g_dmx[u], g_frames[u], BOARD_DMX_FRAME_LEN);
+    }
+    return true;
+}
+
+int main(void) {
+    stdio_init_all();
+    /* Give USB CDC a moment so early boot logs are visible after flash/reboot. */
+    for (int i = 0; i < 40 && !stdio_usb_connected(); i++) {
+        sleep_ms(50);
+    }
+    sleep_ms(200);
+    printf("\nArtNetDMX starting\n");
+    fflush(stdout);
+
+    config_init();
+    channels_init();
+
+    if (!dmx_out_init(&g_dmx[0], BOARD_DMX_A_PIN, pio0)) {
+        printf("DMX A init failed\n");
+    }
+    if (!dmx_out_init(&g_dmx[1], BOARD_DMX_B_PIN, pio1)) {
+        printf("DMX B init failed\n");
+    }
+
+    if (!wifi_mgr_start(config_get())) {
+        printf("WiFi start failed\n");
+        while (true) {
+            tight_loop_contents();
+        }
+    }
+
+    if (!http_server_start()) {
+        printf("HTTP start failed\n");
+    }
+    if (!artnet_start()) {
+        printf("Art-Net start failed\n");
+    }
+
+    static repeating_timer_t dmx_timer;
+    if (!add_repeating_timer_ms(-BOARD_DMX_PERIOD_MS, dmx_timer_cb, NULL, &dmx_timer)) {
+        printf("DMX timer failed\n");
+    } else {
+        printf("DMX output at %d Hz\n", BOARD_DMX_HZ);
+    }
+
+    printf("Ready — mode=%s primary=%s  mDNS http://%s/\n",
+           wifi_mode_name(wifi_mgr_active_mode()),
+           wifi_mgr_ip_str(),
+           wifi_mgr_mdns_name());
+    if (wifi_mgr_ap_up()) {
+        printf("SoftAP http://%s/ (ssid ArtNetDMX)\n", wifi_mgr_ap_ip_str());
+    } else {
+        printf("Joining STA (SoftAP starts only if join fails)...\n");
+    }
+
+    while (true) {
+        wifi_mgr_poll();
+        artnet_poll();
+        tight_loop_contents();
+        sleep_ms(10);
+    }
+}