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

web/scripts/sync-fw-data.mjs

@@ -0,0 +1,15 @@
+import { cp, readdir, rm, mkdir } from "node:fs/promises";
+import { join, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const root = join(__dirname, "..");
+const dist = join(root, "dist");
+const target = join(root, "../firmware/data");
+
+await rm(target, { recursive: true, force: true });
+await mkdir(target, { recursive: true });
+for (const name of await readdir(dist)) {
+  await cp(join(dist, name), join(target, name), { recursive: true });
+}
+console.log("Synced web build → firmware/data");