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/ArduinoJson/extras/tests/JsonVariant/misc.cpp

@@ -0,0 +1,50 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2022, Benoit BLANCHON
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+TEST_CASE("JsonVariant from JsonArray") {
+  SECTION("JsonArray is null") {
+    JsonArray arr;
+    JsonVariant v = arr;
+    REQUIRE(v.isNull() == true);
+  }
+
+  SECTION("JsonArray is not null") {
+    DynamicJsonDocument doc(4096);
+    JsonArray arr = doc.to<JsonArray>();
+    arr.add(12);
+    arr.add(34);
+
+    JsonVariant v = arr;
+
+    REQUIRE(v.is<JsonArray>() == true);
+    REQUIRE(v.size() == 2);
+    REQUIRE(v[0] == 12);
+    REQUIRE(v[1] == 34);
+  }
+}
+
+TEST_CASE("JsonVariant from JsonObject") {
+  SECTION("JsonObject is null") {
+    JsonObject obj;
+    JsonVariant v = obj;
+    REQUIRE(v.isNull() == true);
+  }
+
+  SECTION("JsonObject is not null") {
+    DynamicJsonDocument doc(4096);
+    JsonObject obj = doc.to<JsonObject>();
+    obj["a"] = 12;
+    obj["b"] = 34;
+
+    JsonVariant v = obj;
+
+    REQUIRE(v.is<JsonObject>() == true);
+    REQUIRE(v.size() == 2);
+    REQUIRE(v["a"] == 12);
+    REQUIRE(v["b"] == 34);
+  }
+}