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/arduino-home-assistant-main/examples/led-switch/led-switch.ino

@@ -0,0 +1,50 @@
+#include <Ethernet.h>
+#include <ArduinoHA.h>
+
+#define LED_PIN         9
+#define BROKER_ADDR     IPAddress(192,168,0,17)
+
+byte mac[] = {0x00, 0x10, 0xFA, 0x6E, 0x38, 0x4A};
+
+EthernetClient client;
+HADevice device(mac, sizeof(mac));
+HAMqtt mqtt(client, device);
+HASwitch led("led", false); // "led" is unique ID of the switch. You should define your own ID.
+
+void onBeforeSwitchStateChanged(bool state, HASwitch* s)
+{
+    // this callback will be called before publishing new state to HA
+    // in some cases there may be delay before onStateChanged is called due to network latency
+}
+
+void onSwitchStateChanged(bool state, HASwitch* s)
+{
+    digitalWrite(LED_PIN, (state ? HIGH : LOW));
+}
+
+void setup() {
+    pinMode(LED_PIN, OUTPUT);
+    digitalWrite(LED_PIN, LOW);
+
+    // you don't need to verify return status
+    Ethernet.begin(mac);
+
+    // set device's details (optional)
+    device.setName("Arduino");
+    device.setSoftwareVersion("1.0.0");
+
+    // set icon (optional)
+    led.setIcon("mdi:lightbulb");
+    led.setName("My LED");
+
+    // handle switch state
+    led.onBeforeStateChanged(onBeforeSwitchStateChanged); // optional
+    led.onStateChanged(onSwitchStateChanged);
+
+    mqtt.begin(BROKER_ADDR);
+}
+
+void loop() {
+    Ethernet.maintain();
+    mqtt.loop();
+}