Bump to v0.2.1 (maintenance): CI now verifies the NSIS installer contents via 7z

- Add a 'Verify Windows installer contents' step (7z l shows Step Line.exe +
  uninstall.exe) so the TODO verification items are proven by CI output
- Rebuild 0.2.1 binaries (embedded PCK) and AppImage locally; smoke clean;
  57/57 tests

project.godot

@@ -8,7 +8,7 @@ config_version=5
 
 config/name="Step Line"
 config/description="Workplace security simulation about observation, access verification, and proportionate escalation."
-config/version="0.2.0"
+config/version="0.2.1"
 run/main_scene="res://scenes/main.tscn"
 config/features=PackedStringArray("4.3", "GL Compatibility")