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>

include/wifi_mgr.h

@@ -0,0 +1,25 @@
+#ifndef WIFI_MGR_H
+#define WIFI_MGR_H
+
+#include <stdbool.h>
+#include "config.h"
+
+/**
+ * AP mode: SoftAP only.
+ * STA mode: join LAN; if that fails, SoftAP comes up for recovery.
+ */
+bool wifi_mgr_start(const config_t *cfg);
+/** Call from main loop — runs deferred STA join (STA mode only). */
+void wifi_mgr_poll(void);
+wifi_mode_t wifi_mgr_active_mode(void);
+/** Primary IP for UI (STA if up, else AP). */
+const char *wifi_mgr_ip_str(void);
+const char *wifi_mgr_sta_ip_str(void);
+const char *wifi_mgr_ap_ip_str(void);
+const char *wifi_mgr_mdns_name(void);
+bool wifi_mgr_sta_up(void);
+bool wifi_mgr_ap_up(void);
+bool wifi_mgr_is_up(void);
+const char *wifi_mgr_debug(void);
+
+#endif