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

docs/PINOUT.md

@@ -0,0 +1,22 @@
+# Pinout notes (ESP32-S3-DevKitC-1)
+
+Strapping and USB pins differ by revision — **avoid** GPIO `19–20` for PN532 when using USB-Serial/JTAG on many boards. Prefer **SPI2** on free GPIOs from the [DevKitC-1 user guide](https://docs.espressif.com/projects/esp-dev-kits/en/latest/esp32s3/esp32-s3-devkitc-1/user_guide_v1.1.html).
+
+## Kconfig defaults (examples only)
+
+The firmware Kconfig ships **example** GPIOs:
+
+- **SPI**: MOSI `11`, MISO `13`, SCLK `12`, CS `10`
+- **I2C**: SDA `8`, SCL `9`
+
+**You must verify** these against your PCB/breadboard and PN532 breakout (Adafruit / Elechouse / clones often label SPI and I2C jumpers).
+
+## PN532 wiring checklist
+
+- **SPI**: connect `RSTO`/`RST` to MCU if exposed; some breakouts auto-reset via I2C/SPI activity.
+- **I2C**: set address pins per module (usually **0x24** 7‑bit).
+- **Power**: **3.3V** logic on ESP32; ensure PN532 module is 3.3V compliant (level-shift if using a 5V Arduino-style shield).
+
+## Transport selection
+
+Start with the bus your breakout is jumpered for — **I2C is often simplest** on ESP32 for bring-up; SPI may require **lower clock** initially (e.g. **100 kHz**).