Scaffold PlatformIO project with Docker-based build, test and flash

- pioarduino platform 55.03.312 (Arduino-ESP32 3.3.x / ESP-IDF 5.5),
  board m5stack-stamps3, M5Cardputer 1.1.1
- native env with Unity for host-side tests
- scripts/ci.sh and scripts/flash.sh run PlatformIO in a container
- version injected from git describe
- boot stub shows name, version and pressed keys
- GPL-3.0 license

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

test/test_version/test_version.cpp

@@ -0,0 +1,22 @@
+#include <unity.h>
+#include <cstring>
+
+#include "version.h"
+
+void setUp() {}
+void tearDown() {}
+
+void test_version_is_never_empty() {
+    TEST_ASSERT_TRUE(std::strlen(roro::versionString()) > 0);
+}
+
+void test_product_name() {
+    TEST_ASSERT_EQUAL_STRING("roro9stack", roro::kProductName);
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_version_is_never_empty);
+    RUN_TEST(test_product_name);
+    return UNITY_END();
+}