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/Rtc_by_Makuna/src/RtcUtility.cpp

@@ -0,0 +1,34 @@
+
+#include <Arduino.h>
+#include "RtcUtility.h"
+
+uint8_t BcdToUint8(uint8_t val)
+{
+    return val - 6 * (val >> 4);
+}
+
+uint8_t Uint8ToBcd(uint8_t val)
+{
+    return val + 6 * (val / 10);
+}
+
+uint8_t BcdToBin24Hour(uint8_t bcdHour)
+{
+    uint8_t hour;
+    if (bcdHour & 0x40)
+    {
+        // 12 hour mode, convert to 24
+        bool isPm = ((bcdHour & 0x20) != 0);
+
+        hour = BcdToUint8(bcdHour & 0x1f);
+        if (isPm)
+        {
+           hour += 12;
+        }
+    }
+    else
+    {
+        hour = BcdToUint8(bcdHour);
+    }
+    return hour;
+}