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/examples/WriteRules/WriteRules.ino

@@ -0,0 +1,29 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Write TimeChangeRules to EEPROM.
+// Jack Christensen Mar 2012
+
+#include <Timezone.h>   // https://github.com/JChristensen/Timezone
+
+// US Eastern Time Zone (New York, Detroit)
+TimeChangeRule usEdt = {"EDT", Second, Sun, Mar, 2, -240};    // UTC - 4 hours
+TimeChangeRule usEst = {"EST", First, Sun, Nov, 2, -300};     // UTC - 5 hours
+Timezone usEastern(usEdt, usEst);
+
+void setup()
+{
+    pinMode(13, OUTPUT);
+    usEastern.writeRules(100);    // write rules to EEPROM address 100
+}
+
+void loop()
+{
+    // fast blink to indicate EEPROM write is complete
+    digitalWrite(13, HIGH);
+    delay(100);
+    digitalWrite(13, LOW);
+    delay(100);
+}
+