catalog: harden artifact validation

[BCook98]

Summary

• remove the tracked Paperdrift native binary
• reject committed build artifacts beyond wasm, including native executables and build-output directories
• add validator regression tests and update catalog submission docs

Tests

• python3 .github/scripts/test_validate_game_dir.py
• for d in games//; do [ -d "$d" ] || continue; python3 .github/scripts/validate_game_dir.py "$d"; done

[github-actions]

Smoke screens

Deterministic scripted screens for 0ed1c9e6f4167365581232cb6986130db6fc8869 (what is this?)

games/alan/chess — 8 screens

01-opening.seat0

01-opening.seat1

02-after-1-e4-e5.seat0

02-after-1-e4-e5.seat1

03-after-2-Nf3.seat0

03-after-2-Nf3.seat1

04-after-3-Nxe5.seat0

04-after-3-Nxe5.seat1

games/bcook/blackjack — 14 screens

01-bet.seat0

01-bet.seat1

02-dealt.seat0

02-dealt.seat1

03-decided.seat0

03-decided.seat1

04-hit.seat0

04-hit.seat1

05-payout.seat0

05-payout.seat1

06-ready.seat0

06-ready.seat1

07-next.seat0

07-next.seat1

games/bcook/scratchies — 11 screens

01-counter

02-stand.seat0

02-stand.seat1

03-fresh-card.seat0

03-fresh-card.seat1

04-mid-scratch.seat0

04-mid-scratch.seat1

05-result.seat0

05-result.seat1

06-result-2.seat0

06-result-2.seat1

games/bcook/shellracer — 6 screens

01-start.seat0

01-start.seat1

02-midrace.seat0

02-midrace.seat1

03-nearfinish.seat0

03-nearfinish.seat1

games/laco/paperdrift — 10 screens

01-countdown.seat0

01-countdown.seat1

02-launch.seat0

02-launch.seat1

03-midflight.seat0

03-midflight.seat1

04-chase.seat0

04-chase.seat1

05-results.seat0

05-results.seat1

games/luke/neon-snake — 5 screens

01-start

02-theme_cycled

03-game_over

04-mode_hazards

05-settings_menu