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/session_capture.c

@@ -0,0 +1,129 @@
+#include "nfc_engine/session_capture.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/semphr.h"
+#include <string.h>
+
+#define SESSION_CAPTURE_BYTES (48 * 1024)
+
+static char s_buf[SESSION_CAPTURE_BYTES];
+static size_t s_len;
+static uint32_t s_lines;
+static bool s_full;
+static bool s_deep;
+static SemaphoreHandle_t s_mu;
+
+void session_capture_init(void)
+{
+    s_mu = xSemaphoreCreateMutex();
+    session_capture_clear();
+    s_deep = false;
+}
+
+void session_capture_clear(void)
+{
+    if (s_mu) {
+        xSemaphoreTake(s_mu, portMAX_DELAY);
+    }
+    s_len = 0;
+    s_lines = 0;
+    s_full = false;
+    s_buf[0] = 0;
+    if (s_mu) {
+        xSemaphoreGive(s_mu);
+    }
+}
+
+bool session_capture_is_full(void)
+{
+    return s_full;
+}
+
+bool session_capture_deep_enabled(void) { return s_deep; }
+
+void session_capture_set_deep(bool on) { s_deep = on; }
+
+size_t session_capture_max(void) { return sizeof(s_buf) - 2; }
+
+void session_capture_get_status(size_t *used_bytes, uint32_t *line_count, bool *full)
+{
+    if (s_mu) {
+        xSemaphoreTake(s_mu, portMAX_DELAY);
+    }
+    if (used_bytes) {
+        *used_bytes = s_len;
+    }
+    if (line_count) {
+        *line_count = s_lines;
+    }
+    if (full) {
+        *full = s_full;
+    }
+    if (s_mu) {
+        xSemaphoreGive(s_mu);
+    }
+}
+
+bool session_capture_append_line(const char *line)
+{
+    if (!line || s_full) {
+        return false;
+    }
+    size_t l = strlen(line);
+    size_t need = l + 1; /* newline */
+    if (s_mu) {
+        xSemaphoreTake(s_mu, portMAX_DELAY);
+    }
+    if (s_full || s_len + need >= sizeof(s_buf)) {
+        s_full = true;
+        if (s_mu) {
+            xSemaphoreGive(s_mu);
+        }
+        return false;
+    }
+    memcpy(s_buf + s_len, line, l);
+    s_len += l;
+    s_buf[s_len++] = '\n';
+    s_buf[s_len] = 0;
+    s_lines++;
+    if (s_len + 2 >= sizeof(s_buf)) {
+        s_full = true;
+    }
+    if (s_mu) {
+        xSemaphoreGive(s_mu);
+    }
+    return true;
+}
+
+size_t session_capture_export_size(void)
+{
+    if (s_mu) {
+        xSemaphoreTake(s_mu, portMAX_DELAY);
+    }
+    size_t n = s_len;
+    if (s_mu) {
+        xSemaphoreGive(s_mu);
+    }
+    return n;
+}
+
+const char *session_capture_export_ptr(void) { return s_buf; }
+
+void session_capture_copy_to(char *dst, size_t cap, size_t *out_len)
+{
+    if (s_mu) {
+        xSemaphoreTake(s_mu, portMAX_DELAY);
+    }
+    size_t n = s_len;
+    if (n > cap) {
+        n = cap;
+    }
+    if (dst && n) {
+        memcpy(dst, s_buf, n);
+    }
+    if (out_len) {
+        *out_len = n;
+    }
+    if (s_mu) {
+        xSemaphoreGive(s_mu);
+    }
+}