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/sdkconfig.defaults

@@ -0,0 +1,34 @@
+CONFIG_IDF_TARGET_ESP32S3=y
+CONFIG_ESPTOOLPY_FLASHMODE_QIO=y
+CONFIG_ESPTOOLPY_FLASHFREQ_80M=y
+CONFIG_ESPTOOLPY_FLASHSIZE_8MB=y
+
+CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_240=y
+# Enable if module has PSRAM (e.g. N8R8)
+# CONFIG_SPIRAM=y
+# CONFIG_SPIRAM_MODE_OCT=y
+# CONFIG_SPIRAM_SPEED_80M=y
+
+CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG=y
+CONFIG_ESP_MAIN_TASK_STACK_SIZE=8192
+CONFIG_FREERTOS_HZ=1000
+
+CONFIG_HTTPD_WS_SUPPORT=y
+CONFIG_HTTPD_MAX_REQ_HDR_LEN=1024
+CONFIG_HTTPD_MAX_URI_LEN=512
+CONFIG_ESP_HTTP_CLIENT_ENABLE_HTTPS=y
+
+CONFIG_LWIP_LOCAL_IP4_TTL=64
+CONFIG_ESP_WIFI_STATIC_RX_BUFFER_NUM=10
+CONFIG_ESP_WIFI_DYNAMIC_RX_BUFFER_NUM=32
+
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"
+CONFIG_PARTITION_TABLE_FILENAME="partitions.csv"
+CONFIG_PARTITION_TABLE_OFFSET=0x8000
+
+CONFIG_LOG_DEFAULT_LEVEL_INFO=y
+CONFIG_LOG_MAXIMUM_LEVEL_VERBOSE=y
+
+# mDNS
+CONFIG_MDNS_MAX_SERVICES=10