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/NTPClient/library.properties

@@ -0,0 +1,9 @@
+name=NTPClient
+version=3.2.1
+author=Fabrice Weinberg
+maintainer=Fabrice Weinberg <fabrice@weinberg.me>
+sentence=An NTPClient to connect to a time server
+paragraph=Get time from a NTP server and keep it in sync.
+category=Timing
+url=https://github.com/arduino-libraries/NTPClient
+architectures=*