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/Timezone/keywords.txt

@@ -0,0 +1,9 @@
+TimeChangeRule	KEYWORD1
+Timezone	KEYWORD1
+toLocal	KEYWORD2
+toUTC	KEYWORD2
+utcIsDST	KEYWORD2
+locIsDST	KEYWORD2
+setRules	KEYWORD2
+readRules	KEYWORD2
+writeRules	KEYWORD2