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/Helpers/progmem_emulation.hpp

@@ -0,0 +1,29 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2022, Benoit BLANCHON
+// MIT License
+
+#include <stdint.h>  // uint8_t
+
+#define PROGMEM
+
+class __FlashStringHelper;
+
+inline const void* convertPtrToFlash(const void* s) {
+  return reinterpret_cast<const char*>(s) + 42;
+}
+
+inline const void* convertFlashToPtr(const void* s) {
+  return reinterpret_cast<const char*>(s) - 42;
+}
+
+#define PSTR(X) reinterpret_cast<const char*>(convertPtrToFlash(X))
+#define F(X) reinterpret_cast<const __FlashStringHelper*>(PSTR(X))
+
+inline uint8_t pgm_read_byte(const void* p) {
+  return *reinterpret_cast<const uint8_t*>(convertFlashToPtr(p));
+}
+
+#define ARDUINOJSON_DEFINE_PROGMEM_ARRAY(type, name, value)        \
+  static type const ARDUINOJSON_CONCAT2(name, _progmem)[] = value; \
+  static type const* name = reinterpret_cast<type const*>(         \
+      convertPtrToFlash(ARDUINOJSON_CONCAT2(name, _progmem)));