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/ESP32_UniClock2/dummy.ino

@@ -0,0 +1,20 @@
+#ifdef DUMMY
+
+//Dummy clock driver for sensor box / mqtt sensors
+
+char tubeDriver[] = "DUMMY";
+int maxDigits = 6;
+
+void setup_pins() {
+  DPRINTLN("Dummy display: no pins are used");
+}
+
+#if defined(ESP32)
+void IRAM_ATTR writeDisplay() {} 
+#else
+void ICACHE_RAM_ATTR writeDisplay(){}
+#endif
+
+void clearTubes() {}
+void writeDisplaySingle() {}
+#endif