feat(karaoke): add 4 missing Blazor Razor workflow files
- KaraokeJourney.razor: 6-step end-to-end session workflow tracker
- PeakWarning.razor: Peak hours pricing warning with cost estimator
- RoomExtend.razor: Room extension dialog with time options and preview
- RoomReset.razor: Room cleanup/reset checklist with progress tracking
All files follow existing Karaoke patterns (PosLayout, PosBase, FormatPrice,
NavigateTo, bilingual comments, section markers, CSS vars, Lucide icons,
Vietnamese demo data).
Co-authored-by: Velik <hongochai10@users.noreply.github.com>
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