#21874 webviews: a gallery entry for the Chief picture crop

#21737 added pages/home-channels/PictureCrop.tsx without a gallery entry, so test/gallery-coverage.test.ts fails on feat-cmux-next itself. On a PR, that finding fails only PRs that touch the file or the home-channels gallery: #21623 and #21747 so far.

The Chief sheet shows the crop only after a file is chosen, so the page entry never reaches it. This adds a standalone entry, pages.home-channels.picture-crop, using the page's real strings and a sample still drawn as an inline SVG. It has three variants: wide, tall, and zoomed and moved. I added an entry instead of an allowlist line because the allowlist is meant to only shrink.

Verification

• At fa5ed5c04, the feat-cmux-next tip, bun test test/gallery-coverage.test.ts fails with + "pages/home-channels/PictureCrop.tsx#PictureCrop". With this change: 6 pass.
• gallery-manifest and gallery-entry-store tests pass. bun run typecheck finds no type errors, and vp fmt --check is clean.
• Not checked locally: how the entry renders. CI's gallery play renders every entry.

Changelog

none

🤖 Generated with Claude Code

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Summary by cubic

Adds a gallery entry for the Chief picture crop so gallery-coverage passes on feat-cmux-next. The component added in #21737 had no gallery entry, and since the crop only appears after a file is chosen, the page entry never covers it.

• Adds pages.home-channels.picture-crop using the page's real strings and an inline SVG sample so drag and zoom are visible.
• Provides landscape, portrait, and zoomed-and-moved variants.
• Adds an entry instead of an allowlist line because the allowlist is meant to only shrink.