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/pn532_host/Kconfig

@@ -0,0 +1,84 @@
+menu "PN532 Host"
+
+choice PN532_TRANSPORT
+    prompt "PN532 bus"
+    default PN532_TRANSPORT_SPI
+    config PN532_TRANSPORT_SPI
+        bool "SPI"
+    config PN532_TRANSPORT_I2C
+        bool "I2C"
+    config PN532_TRANSPORT_HSU
+        bool "UART (HSU)"
+endchoice
+
+config PN532_SPI_HOST
+    int "SPI host (2=SPI2, 3=SPI3)"
+    default 2
+    depends on PN532_TRANSPORT_SPI
+
+config PN532_SPI_MOSI_GPIO
+    int "SPI MOSI GPIO"
+    default 11
+    depends on PN532_TRANSPORT_SPI
+
+config PN532_SPI_MISO_GPIO
+    int "SPI MISO GPIO"
+    default 13
+    depends on PN532_TRANSPORT_SPI
+
+config PN532_SPI_SCLK_GPIO
+    int "SPI SCLK GPIO"
+    default 12
+    depends on PN532_TRANSPORT_SPI
+
+config PN532_SPI_CS_GPIO
+    int "SPI CS GPIO"
+    default 10
+    depends on PN532_TRANSPORT_SPI
+
+config PN532_SPI_CLOCK_HZ
+    int "SPI clock Hz"
+    default 100000
+    depends on PN532_TRANSPORT_SPI
+
+config PN532_I2C_PORT
+    int "I2C port"
+    default 0
+    depends on PN532_TRANSPORT_I2C
+
+config PN532_I2C_SDA_GPIO
+    int "I2C SDA GPIO"
+    default 8
+    depends on PN532_TRANSPORT_I2C
+
+config PN532_I2C_SCL_GPIO
+    int "I2C SCL GPIO"
+    default 9
+    depends on PN532_TRANSPORT_I2C
+
+config PN532_I2C_ADDR
+    hex "PN532 I2C 7-bit address"
+    default 0x24
+    depends on PN532_TRANSPORT_I2C
+
+config PN532_HSU_UART_NUM
+    int "UART num for HSU"
+    default 1
+    depends on PN532_TRANSPORT_HSU
+
+config PN532_HSU_TX_GPIO
+    int "UART TX GPIO"
+    default 17
+    depends on PN532_TRANSPORT_HSU
+
+config PN532_HSU_RX_GPIO
+    int "UART RX GPIO"
+    default 18
+    depends on PN532_TRANSPORT_HSU
+
+config PN532_HSU_BAUD
+    int "UART baud"
+    default 115200
+    depends on PN532_TRANSPORT_HSU
+
+endmenu