Import ESP_UniClock (upstream 1189810)

Vendored from https://github.com/gpeter62/ESP_UniClock: the sketch
source, the web UI and the libraries the ESP8266 build needs, unpacked
from the bundled zips. Adds a PlatformIO project for the ESP-12. The
source is unchanged; local changes follow as separate commits.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

firmware/uniclock/lib/ArduinoJson/extras/ci/particle.sh

@@ -0,0 +1,10 @@
+#!/bin/sh -ex
+
+BOARD=$1
+
+cd "$(dirname "$0")/../../"
+
+cp extras/particle/src/smocktest.ino src/
+cp extras/particle/project.properties ./
+
+particle compile "$BOARD"