Keep screenshot fixtures in sync

[austin-smith]

What Changed

• Added a shared screenshot fixture catalog used by both the app and UI test targets.
• Updated screenshot capture to cover all ten bundled game fixtures.
• Removed inconsistent “fresh deal” fixture metadata while preserving meaningful mode qualifiers.
• Refreshed the tracked iOS and macOS README screenshots.

Why

The screenshot UI test duplicated the app’s fixture list and had fallen out of sync, so only four of ten game variants were captured. Sharing one ordered catalog prevents that drift.

Validation

• Ran the macOS test suite: 541 tests passed with 0 failures; 10 fixture generators skipped as designed.
• Built the macOS app successfully.
• Ran dark-mode Fastlane capture on iPhone 17 Pro Max and iPhone 17 Pro.
• Verified 20 generated PNGs at the expected dimensions.
• Visually reviewed the newly included game screenshots.
• Ran git diff --check.

UI Changes

Updated the tracked iOS and macOS screenshots to reflect the current dark appearance.

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