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/api/Print.h

@@ -0,0 +1,33 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2022, Benoit BLANCHON
+// MIT License
+
+#pragma once
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+class Print {
+ public:
+  virtual ~Print() {}
+
+  virtual size_t write(uint8_t) = 0;
+  virtual size_t write(const uint8_t *buffer, size_t size) = 0;
+
+  size_t write(const char *str) {
+    if (!str)
+      return 0;
+    return write(reinterpret_cast<const uint8_t *>(str), strlen(str));
+  }
+
+  size_t write(const char *buffer, size_t size) {
+    return write(reinterpret_cast<const uint8_t *>(buffer), size);
+  }
+};
+
+class Printable {
+ public:
+  virtual ~Printable() {}
+  virtual size_t printTo(Print &p) const = 0;
+};