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

scripts/version.py

@@ -0,0 +1,13 @@
+# Injects the firmware version from `git describe` (semver tags like v0.1.0).
+import subprocess
+
+Import("env")  # noqa: F821  (provided by PlatformIO)
+
+try:
+    version = subprocess.check_output(
+        ["git", "describe", "--tags", "--always", "--dirty"], text=True
+    ).strip()
+except Exception:
+    version = "unknown"
+
+env.Append(CPPDEFINES=[("RORO_VERSION", '\\"%s\\"' % version)])  # noqa: F821