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/ESPAsyncTCP/library.properties

@@ -0,0 +1,9 @@
+name=ESP AsyncTCP
+version=2.0.1
+author=Phil Bowles
+maintainer=Phil Bowles
+sentence=BUGFIXED Async TCP Library for ESP8266
+paragraph=BUGFIXED Async TCP Library for ESP8266
+category=Communication
+url=https://github.com/philbowles/ESPAsyncTCP
+architectures=*