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/MsgPackSerializer/misc.cpp

@@ -0,0 +1,46 @@
+#include <ArduinoJson.h>
+#include <catch.hpp>
+#include <limits>
+
+template <typename T>
+void check(T value, const std::string &expected) {
+  DynamicJsonDocument doc(4096);
+  doc.to<JsonVariant>().set(value);
+  char buffer[256] = "";
+  size_t returnValue = serializeMsgPack(doc, buffer, sizeof(buffer));
+  REQUIRE(expected == buffer);
+  REQUIRE(expected.size() == returnValue);
+}
+
+TEST_CASE("serializeMsgPack(MemberProxy)") {
+  DynamicJsonDocument doc(4096);
+  deserializeJson(doc, "{\"hello\":42}");
+  JsonObject obj = doc.as<JsonObject>();
+  std::string result;
+
+  serializeMsgPack(obj["hello"], result);
+
+  REQUIRE(result == "*");
+}
+
+TEST_CASE("serializeMsgPack(ElementProxy)") {
+  DynamicJsonDocument doc(4096);
+  deserializeJson(doc, "[42]");
+  JsonArray arr = doc.as<JsonArray>();
+  std::string result;
+
+  serializeMsgPack(arr[0], result);
+
+  REQUIRE(result == "*");
+}
+
+TEST_CASE("serializeMsgPack(JsonVariantSubscript)") {
+  DynamicJsonDocument doc(4096);
+  deserializeJson(doc, "[42]");
+  JsonVariant var = doc.as<JsonVariant>();
+  std::string result;
+
+  serializeMsgPack(var[0], result);
+
+  REQUIRE(result == "*");
+}