WLED Unauthenticated Configuration Disclosure via /json/cfg and Global Settings-PIN Lock State

WLED's GET /json/cfg endpoint (registered in wled00/wled_server.cpp) calls serveJson() with no settings-PIN check, unlike the /edit endpoint which explicitly checks correctPIN, disclosing the device's general configuration (network, hardware, LED setup) to any unauthenticated client on the network. Separately, the settings-PIN unlock state is tracked via a single global boolean `correctPIN` (wled00/wled.h), not per-session state: once any single client submits the correct 4-digit PIN via POST /json, correctPIN becomes true for every client, granting all subsequent unauthenticated clients full configuration-write access (OTA firmware updates, WiFi reconfiguration, factory reset) until the device reboots.