Add PlatformIO project setup, local libraries, and PCB Gerber files

- Add platformio.ini for ESP32 DevKit (Arduino framework, espressif32 6.10.0)
- Vendor ArduinoJson, MPU6050_tockn, SCServo, Simple_FOC, and WebSockets
  so a fresh clone builds without downloading dependencies
- Add .gitignore rules for PlatformIO/IDE build artifacts
- Add controller PCB Gerber and drill files

3.Software/libraries/ArduinoJson/extras/tests/JsonVariant/add.cpp

@@ -0,0 +1,46 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2023, Benoit BLANCHON
+// MIT License
+
+#include <ArduinoJson.h>
+#include <stdint.h>
+#include <catch.hpp>
+
+TEST_CASE("JsonVariant::add()") {
+  DynamicJsonDocument doc(4096);
+  JsonVariant var = doc.to<JsonVariant>();
+
+  SECTION("add integer to new variant") {
+    var.add(42);
+
+    REQUIRE(var.as<std::string>() == "[42]");
+  }
+
+  SECTION("add const char* to new variant") {
+    var.add("hello");
+
+    REQUIRE(var.as<std::string>() == "[\"hello\"]");
+  }
+
+  SECTION("add std::string to new variant") {
+    var.add(std::string("hello"));
+
+    REQUIRE(var.as<std::string>() == "[\"hello\"]");
+  }
+
+  SECTION("add integer to integer") {
+    var.set(123);
+
+    var.add(456);  // no-op
+
+    REQUIRE(var.as<std::string>() == "123");
+  }
+
+  SECTION("add integer to object") {
+    var["val"] = 123;
+
+    var.add(456);  // no-op
+
+    REQUIRE(var.as<std::string>() == "{\"val\":123}");
+  }
+}