Two unrelated polish fixes.
espidf_compiler: headers that resolve to an arduino-esp32 CORE lib
(WebServer, WiFi, …) were correctly skipped from the user-lib merge but
then fell through to a scary "Library for <X> not found — build may
fail" warning — even though the build succeeds because the symbols are
compiled into the core. Now logs an accurate "provided by arduino-esp32
core — already compiled in, not merging". Same treatment for core
headers that aren't standalone lib dirs (Udp.h, IPAddress.h,
WiFiUdp.h, …) via a new _CORE_ESP32_HEADERS allowlist.
SimulatorCanvas: the WiFi badge's "open IoT gateway" click now consults
an optional window.__velxio_iot_gateway_open_gate__ hook before opening
the gateway tab. A private overlay can install it to gate the gateway
behind a paid plan and show an in-place upgrade modal instead of dumping
a 402 page in a new tab. OSS builds have no hook → opens normally. The
check is synchronous so it doesn't trip popup blockers.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>