Address browser test review fixes

[KSemenenko]

Summary

• make the recording file harness advance even when requestVideoFrameCallback never fires
• cap the Learn startup trace RAF loop without the extra pass
• record the current workspace-only branch workflow preference in AGENTS

Verification

• dotnet test tests/PrompterOne.App.UITests/PrompterOne.App.UITests.csproj --filter "FullyQualifiedName=PrompterOne.App.UITests.GoLiveShellSessionFlowTests.GoLivePage_StartRecording_FilePickerSave_ProducesDecodableProgramVideoAndAudio"
• dotnet test tests/PrompterOne.App.UITests/PrompterOne.App.UITests.csproj --filter "FullyQualifiedName=PrompterOne.App.UITests.LearnStartupAlignmentTests.LearnScreen_DemoStartup_HidesFocusRowUntilOrpLayoutIsReady" --no-build
• dotnet build PrompterOne.slnx -warnaserror
• dotnet test PrompterOne.slnx
• dotnet format PrompterOne.slnx
• dotnet build PrompterOne.slnx -warnaserror
• dotnet test PrompterOne.slnx

[Copilot]

Pull request overview

This PR tightens up a couple of flaky browser-driven UI test harness behaviors and records an agent workflow preference, improving reliability of Playwright-based verification in the PrompterOne UI test suite.

Changes:

• Update the recording file harness to advance on a timeout when requestVideoFrameCallback is unavailable or never fires.
• Fix the Learn startup trace sampling loop to cap the RAF passes without an extra iteration.
• Document a preference to work on the active workspace branch rather than using temporary worktrees by default.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
tests/PrompterOne.App.UITests/Media/recording-file-harness.js	Makes frame-wait logic progress even when requestVideoFrameCallback doesn’t fire, reducing test hangs/flakiness.
tests/PrompterOne.App.UITests/Learn/LearnStartupAlignmentTests.cs	Adjusts RAF pass counting to avoid an extra capture pass and better honor the max-pass cap.
AGENTS.md	Adds guidance about avoiding throwaway worktrees/copies when the current workspace branch is available.

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