fix(web): enable miniapp detail scrolling

[kev1n77]

Summary

Fix scrolling for MiniApp detail content in the stable-height gallery modal.

Type and Areas

Type:

Bug fix / UI/UX / test

Areas:

Web UI

Motivation / Impact

The stable-height MiniApp detail modal used overflow: hidden on its content area, preventing users from viewing permissions, ratings, changelog entries, and release history beyond the visible viewport.

The detail content now uses an independent vertical scroll container while keeping the modal header and footer actions available.

Verification

• pnpm --dir src/web-ui run test:run src/app/components/GalleryLayout/GalleryDetailModal.presentation.test.ts
• pnpm run check:web
• git diff --check

All checks passed.

Reviewer Notes

• The change is limited to the shared gallery detail modal styling and its presentation contract test.
• overscroll-behavior: contain keeps scrolling within the modal content area.
• No persisted data, API contracts, localization, or migration behavior is affected.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.