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/memoryUsage.cpp

@@ -0,0 +1,41 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2022, Benoit BLANCHON
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+#include <string>
+
+TEST_CASE("JsonVariant::memoryUsage()") {
+  DynamicJsonDocument doc(4096);
+  JsonVariant var = doc.to<JsonVariant>();
+
+  SECTION("returns 0 if uninitialized") {
+    JsonVariant unitialized;
+    REQUIRE(unitialized.memoryUsage() == 0);
+  }
+
+  SECTION("returns size of object") {
+    JsonObject obj = var.to<JsonObject>();
+    obj["hello"] = 42;
+    REQUIRE(var.memoryUsage() == JSON_OBJECT_SIZE(1));
+  }
+
+  SECTION("returns size of array") {
+    JsonArray arr = var.to<JsonArray>();
+    arr.add(42);
+    REQUIRE(var.memoryUsage() == JSON_ARRAY_SIZE(1));
+  }
+
+  SECTION("returns size of owned string") {
+    var.set(std::string("hello"));
+    REQUIRE(var.memoryUsage() == 6);
+    REQUIRE(var.memoryUsage() == doc.memoryUsage());
+  }
+
+  SECTION("returns size of owned raw") {
+    var.set(serialized(std::string("hello")));
+    REQUIRE(var.memoryUsage() == 6);
+    REQUIRE(var.memoryUsage() == doc.memoryUsage());
+  }
+}