Drag-and-drop script block rearrangement

Summary

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

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.

@byskyphy

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.

Fix editor rendered authoring board