Implements Phase 4 of the z-machine compatibility plan.
Creates automated regression tests that smoke-test all supported games
(V3, V5, V8) by loading each story, executing basic commands, and verifying
the interpreter doesn't crash.
Key features:
- Parametrized test covering 7 games (zork1, curses, photopia, Tangle,
shade, LostPig, anchor)
- QuietScreen class that disables [MORE] prompts for unattended testing
- AutoInputStream that auto-feeds commands then exits cleanly
- Tests verify: no crashes, unimplemented opcodes, and minimum instruction count
- All tests pass in ~2 seconds
Tests skip gracefully if story files aren't present, making this safe to
run in CI or on systems without all game files.
