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/CMakeLists.txt

@@ -0,0 +1,25 @@
+# ArduinoJson - https://arduinojson.org
+# Copyright © 2014-2022, Benoit BLANCHON
+# MIT License
+
+cmake_minimum_required(VERSION 3.15)
+
+if(ESP_PLATFORM)
+   # Build ArduinoJson as an ESP-IDF component
+   idf_component_register(INCLUDE_DIRS src)
+   return()
+endif()
+
+project(ArduinoJson VERSION 6.19.4)
+
+if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
+    include(CTest)
+endif()
+
+add_subdirectory(src)
+
+if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME AND BUILD_TESTING)
+	include(extras/CompileOptions.cmake)
+	add_subdirectory(extras/tests)
+	add_subdirectory(extras/fuzzing)
+endif()