perf: add responsive capture presentations and stable cards

[rwang23]

Summary

• Generate integrity-bound 320px, 480px, and 960px presentation PNGs from each preserved real-app evidence capture.
• Use responsive Gallery media, explicit original-evidence access, localized details, and a cover-art fallback when a presentation request fails.
• Reuse Theme Manager cards by key; load 320px thumbnails only when visible or near-visible, and keep the 960px detail surface separate.

Verification

• npm run check
• npm run generate:check
• Isolated local Gallery browser QA: ordinary browsing requested only presentation assets; original evidence opened only through its explicit action; an aborted presentation request fell back to reviewed cover art without requesting the original capture.

Closes #11

[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Superseded by #26, now merged into main at e2ed6e8.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.