Add PN532 toolkit firmware, web UI, and embedded SPIFFS assets

Includes ESP-IDF NFC stack (deep capture, 4K Classic geometry, UL write API,
open SoftAP), React dashboard with live tag diagnostics, and docs. README
updated for APIs and lab Wi-Fi defaults.

Made-with: Cursor

firmware/components/nfc_engine/include/nfc_engine/jobs.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "esp_err.h"
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void (*job_progress_cb_t)(int pct, const char *msg, void *ctx);
+
+typedef struct {
+    uint32_t id;
+    char name[32];
+    volatile int pct;
+    volatile int done;
+} nfc_job_t;
+
+uint32_t jobs_create(const char *name);
+void jobs_set_progress(uint32_t id, int pct, const char *msg);
+void jobs_finish(uint32_t id);
+
+#ifdef __cplusplus
+}
+#endif