Show next/previous blocks during recording

[KSemenenko]

Summary

Add a display toggle that shows the next and previous blocks while recording so the performer stays oriented.

Source

• Category: Recording & Exporting
• Feedback video: https://youtu.be/IeUoMyx7dKE?t=40m29s

Acceptance criteria

• Recording mode can show previous and next script blocks around the active block.
• The toggle helps orientation without obscuring recording controls or active text.
• 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 442021f.

What changed:

• Added a Go Live recording cue toggle in the top bar.
• While recording, the program monitor can show compact previous/current/next script block context.
• Added in-overlay next/previous cue controls so the active recording block can advance without covering the recording/streaming controls.
• Added stable data-test selectors plus bUnit and Playwright coverage for the recording context flow.

Verification passed:

• dotnet build ./PrompterOne.slnx -warnaserror --no-restore
• dotnet test --project tests/PrompterOne.Web.Tests/PrompterOne.Web.Tests.csproj --no-build -- --no-ansi --no-progress (620/620)
• dotnet test --project tests/PrompterOne.Web.UITests.Studio/PrompterOne.Web.UITests.Studio.csproj --no-build -- --no-ansi --no-progress (39/39)
• dotnet test @./tests/dotnet-test-progress.rsp --solution ./PrompterOne.slnx (1171/1171)

Ready for review; leaving the issue open for human verification.