feat: add focal-aware rendering safeguards

[rwang23]

Summary

• Replaced centered source-art cropping with focal-cover renderer v3 and directional safe-area grading.
• Added a 2560 x 1440, 16:9 baseline for new source art, with named reviewed legacy exceptions only.
• Added reproducible contact sheets, safe-area fixtures, and approval records for all 68 catalog images.
• Updated contrast guards, refreshed the 136 captured Full Skin modes, and made the desktop check self-sufficient for required capture thumbnails.

Root cause

Generated previews used a fixed centered crop and a left-only safe-area assumption. The desktop check also compiled Tauri configuration without preparing the required bundled screenshot directory.

Verification

• npm run check
• Isolated Gallery browser QA for mode selection, search, language switching, desktop layout, and 390 px mobile layout.
• Isolated ChatGPT Beta 26.715.3651.0 capture: 136 unique modes, 5.6 Sol Max label, and runtime cleanup readback.
• Independent acceptance pass, staged-diff review, git diff --check, and workflow lint.

Boundaries

• Existing 1536 x 1024 images remain explicitly named legacy exceptions. New images must meet the new baseline.
• The capture verifies the current runtime v2. Runtime v3 and physical macOS verification remain separate pending work.

Closes #6

[rwang23]

Superseded by #26, now merged into main at e2ed6e8. This branch head is already included in main; closing the draft avoids duplicate review and merge work.