Export individual takes separately

[KSemenenko]

Summary

Export recorded takes as individual files separated by element/block, rather than one massive continuous file.

Source

• Category: Recording & Exporting
• Feedback video: https://youtu.be/IeUoMyx7dKE?t=38m44s

Acceptance criteria

• Users can export takes as separate files associated with their source element/block.
• Export naming and grouping make it clear which block each take belongs to.
• 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 and pushed to main in commit 5a9c25a.

What changed:

• Go Live recording filenames are now block-aware (take NN + source block title).
• Moving previous/next in the recording block cue overlay while recording now rotates the MediaRecorder take: the current take is finalized/exported, then a new take starts for the newly active block.
• File-picker recording harness now tracks multiple saved take files, and browser coverage verifies separate take-01 / take-02 exports.

Verification passed:

• dotnet build ./PrompterOne.slnx -warnaserror --no-restore
• dotnet test --project tests/PrompterOne.Web.Tests/PrompterOne.Web.Tests.csproj --no-build -- --treenode-filter "/*/*/GoLiveSessionInteractionTests/*" --no-ansi --no-progress
• dotnet test --project tests/PrompterOne.Web.UITests.Studio/PrompterOne.Web.UITests.Studio.csproj --no-build -- --treenode-filter "/*/*/GoLiveShellSessionFlowTests/GoLivePage_RecordingBlockNavigation_FilePickerSave_ExportsSeparateBlockTakeFiles" --no-ansi --no-progress
• dotnet test --project tests/PrompterOne.Web.Tests/PrompterOne.Web.Tests.csproj --no-build -- --no-ansi --no-progress
• dotnet test --project tests/PrompterOne.Web.UITests.Studio/PrompterOne.Web.UITests.Studio.csproj --no-build -- --no-ansi --no-progress
• dotnet test @./tests/dotnet-test-progress.rsp --solution ./PrompterOne.slnx (1173/1173 passed)

Please review when ready. I left the issue open for your verification.