Drag-and-drop script block rearrangement

[KSemenenko]

Summary

Build a drag-and-drop feature for rearranging script blocks (similar to Notion or Kanban boards) to avoid cutting and pasting text.

Source

• Category: Script Editing
• Feedback video: https://youtu.be/IeUoMyx7dKE?t=46m52s

Acceptance criteria

• Users can rearrange script blocks through drag-and-drop instead of manual cut/paste.
• Reordering updates the underlying script order reliably and preserves block content.
• The interaction has accessible keyboard or fallback affordances where feasible.
• Add or update browser/UI test coverage for the relevant user flow.
• Solution tests pass before the issue is marked ready for user verification.

[KSemenenko]

Implemented in commit c95d95c.

Scope:

• Added native drag-and-drop reordering for script blocks in the rendered Cards editor view.
• Added accessible fallback move-up/move-down controls with localized labels across supported UI languages.
• Reordering moves the exact source block range, preserving the block header and body text while updating the underlying script order.
• Added unit coverage for source-range reorder behavior and browser UI coverage for fallback controls plus drag-and-drop.

Verification:

• dotnet build ./PrompterOne.slnx -warnaserror --no-restore
• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.Tests/PrompterOne.Web.Tests.csproj -- --treenode-filter "///EditorRenderedBlockReorderServiceTests/*"
• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.UITests.Editor/PrompterOne.Web.UITests.Editor.csproj -- --treenode-filter "///EditorRenderedViewFlowTests/*"
• dotnet test @./tests/dotnet-test-progress.rsp --solution ./PrompterOne.slnx: passed 1142/1142

Ready for review @byskyphy.