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/PubSubClient/library.json

@@ -0,0 +1,18 @@
+{
+    "name": "PubSubClient",
+    "keywords": "ethernet, mqtt, m2m, iot",
+    "description": "A client library for MQTT messaging. MQTT is a lightweight messaging protocol ideal for small devices. This library allows you to send and receive MQTT messages. It supports the latest MQTT 3.1.1 protocol and can be configured to use the older MQTT 3.1 if needed. It supports all Arduino Ethernet Client compatible hardware, including the Intel Galileo/Edison, ESP8266 and TI CC3000.",
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/knolleary/pubsubclient.git"
+    },
+    "version": "2.8",
+    "exclude": "tests",
+    "examples": "examples/*/*.ino",
+    "frameworks": "arduino",
+    "platforms": [
+        "atmelavr",
+        "espressif8266",
+        "espressif32"
+    ]
+}