Add ability to insert contextual notes in prep mode

[KSemenenko]

Summary

Allow performers to add their own contextual notes inside the prep mode.

Source

• Category: Teleprompter & Prep
• Feedback video: https://youtu.be/IeUoMyx7dKE?t=31m19s

Acceptance criteria

• Prep mode lets performers add contextual notes tied to the script or selected section.
• Notes persist locally and are visible in the prep workflow without corrupting script source 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 f07a4bb and pushed to main.

What changed:

• Added a localized Prep notes panel inside Learn/Prep mode.
• Notes are stored locally in browser settings under a dedicated prep-notes store and are tied to the current script plus current sentence/section context.
• Added note input keyboard containment so prep-note typing does not trigger reader shortcuts.
• Added Learn agent/Spotlight tool descriptors for listing and adding prep notes.
• Added responsive styling so the notes panel does not push reader controls off mobile viewports.
• Added bUnit and browser coverage proving notes persist locally and do not modify the script source.

Verification:

• dotnet format ./PrompterOne.slnx --verify-no-changes --no-restore --include <changed C# and Razor files>
• 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 "///LearnKeyboardShortcutTests/|//*/ScreenShellContractTests/LearnPage_RendersCenteredRsvpSurfaceAndInitializesTimeline"
• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.UITests.Reader/PrompterOne.Web.UITests.Reader.csproj -- --treenode-filter "///LearnPrepNotesFlowTests/*"
• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.UITests.Reader/PrompterOne.Web.UITests.Reader.csproj -- --treenode-filter "///ResponsiveLayoutTests/LearnRoute_KeepsPrimaryControlsVisibleAcrossResponsiveViewports*"
• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.Tests/PrompterOne.Web.Tests.csproj (626/626 passed)
• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.UITests.Reader/PrompterOne.Web.UITests.Reader.csproj (173/173 passed)
• dotnet test @./tests/dotnet-test-progress.rsp --solution ./PrompterOne.slnx (1183/1183 passed)

@byskyphy please review when ready.

[KSemenenko]

Follow-up fix completed in local main commit cef8cf9 (pending push): Prep Notes now has a real collapse/expand toggle with aria-expanded, and the browser test verifies collapse, hidden textarea state, re-expand, note add, persistence, and no editor-source mutation.

Verification completed on 2026-04-26:

• dotnet test @./tests/dotnet-test-progress.rsp --project ./tests/PrompterOne.Web.UITests.Reader/PrompterOne.Web.UITests.Reader.csproj: 176/176 passed
• dotnet test @./tests/dotnet-test-progress.rsp --solution ./PrompterOne.slnx: 1191/1191 passed
• Release publish passed locally, with the expected local wasm-tools optimization warning.

Release-version comment still needs to be added after the release containing this follow-up ships.