test(scoreboard): assert the themed pill switch

docs/ai/ui-surface.md

@@ -41,7 +41,7 @@ Placement math itself is covered by `WindowPlacementTests` (pure function, no HW
 - Layout persists to SQLite (`Microsoft.Data.Sqlite`); scenes/sources/asset bytes stored in the DB, asset identity is a SHA-256 content hash (1:M reuse, no file paths — assets are always available). Loaded sources always derive `IsBackground` from `Type` (OR'd with the persisted column, so legacy DisplayCapture backdrops keep their flag) — pre-derivation rows with `IsBackground=0` heal on load
 - **Element z-order is a unified space, not per-table (2026-09-20):** `Source` and `WebcamSceneConfig` live in different tables, and a webcam can be interleaved between sources in a scene. Both tables' `SortOrder` is stamped from the SAME counter — the element's index within `scene.Elements` — and `Load` merges the two tables' rows per scene by that shared z (tie-break sources-first, so legacy per-table rows read back stacked the way they were saved). Never re-introduce per-type sort counters + "append all Sources then all configs", or a webcam slotted mid-stack reverts on reload (creator-reproduced bug).
 - **Five-scene catalog (`Models/SceneCatalog.cs`):** the product is exactly Starting/Live/BRB/Chat/Ending — work with less, never more (the escape hatch for "more" is OBS). Scenes are matched **by name** (`SceneCatalog.Is`, case-insensitive trim). Empty DBs seed all five; the scenes-header "+" (`ShowAddScene`/`MissingScenes` on `MainViewModel`) only appears while ≥1 canonical scene is missing and its menu lists only the missing ones, re-adding them by name (`AddSceneCommand`). Renaming a canonical scene makes it missing again; `AddScene` rejects non-canonical names.
-- Theming: all custom styles live in `Themes/Controls.xaml`, merged in `App.xaml` — never duplicate styles per-window (dialog duplicates were consolidated into this dictionary). **Every control in the app carries a theme style (TASK 58, 2026-10-21):** an unstyled `ComboBox`/`CheckBox` falls back to the **light WPF system template** (grey border, system arrow, white popup list) and sticks out of the dark panels — the properties panel's drop-downs had been hand-painted with a `Background`/`Foreground` instead of a style (the chat Font drop-down was a copy of that), and every check box was default. The rule now: `ComboBox` → `YtComboBox`, `CheckBox` → `YtCheckBox`, the dense properties fields → `YtTextBoxCompact` (`BasedOn YtTextBox`: 11px, padding 4,2) — **no hand-painted `Background`/`BorderBrush` on a themed control**. `ytLive.Tests/PropertiesStyleTests.cs` is the guard: it fails if an unstyled drop-down, check box or properties field comes back — **but that guard sees only those three control types**, so a picker built as something else (a `Button` + a code-built `ContextMenu`) slipped through it and the creator had to ask twice (TASK 63)
+- Theming: all custom styles live in `Themes/Controls.xaml`, merged in `App.xaml` — never duplicate styles per-window (dialog duplicates were consolidated into this dictionary). **Every control in the app carries a theme style (TASK 58, 2026-10-21):** an unstyled `ComboBox`/`CheckBox` falls back to the **light WPF system template** (grey border, system arrow, white popup list) and sticks out of the dark panels — the properties panel's drop-downs had been hand-painted with a `Background`/`Foreground` instead of a style (the chat Font drop-down was a copy of that), and every check box was default. The rule now: `ComboBox` → `YtComboBox`, property-panel switches → `PropertyPillCheck` (plain check boxes may use `YtCheckBox`), the dense properties fields → `YtTextBoxCompact` (`BasedOn YtTextBox`: 11px, padding 4,2) — **no hand-painted `Background`/`BorderBrush` on a themed control**. `ytLive.Tests/PropertiesStyleTests.cs` is the guard: it fails if an unstyled drop-down, check box or properties field comes back — **but that guard sees only those three control types**, so a picker built as something else (a `Button` + a code-built `ContextMenu`) slipped through it and the creator had to ask twice (TASK 63)
 - **The properties panel is a HIERARCHY (TASK 59, 2026-10-21):** a **title owns its content, and the content is indented one level (10px) under it** — the creator's ruling: *"the 'drag to move' help text needs to be indented under 'Mirror Rect' to show parentage … same with Geometry, Border Color, Border Thickness … Remove should be indented under Background as should Blur … Strength should be indented under Blur."* So the webcam's block reads `Shape` (the mirror switch + the shape choice) → `Geometry` → `Border Color` → `Border Thickness` → `Background` (Remove, Blur, and Strength one level deeper under Blur), each title SemiBold at 11px `#a0a0b0` like the existing ones. **The shape is a CHOICE, not a toggle button:** `IsRectShape`/`IsRoundShape` on `SceneElement` are two settable bools and the panel shows them as two `SegmentToggle` options (Rect | Circle) with **Rect selected by default** (an element that never picked a shape is a rect) — the old single button showed the *next* action ("Round"), which is why the creator could not tell what the camera was. The mutual exclusion lives in the MODEL (each setter flips through `ToggleClipShape()` and both props are re-raised), **not** in a WPF `RadioButton` group — a RadioButton group unchecks its siblings by setting `IsChecked` in code, which silently kills the binding (stackoverflow 7376373). Each setter always re-raises, so a refused write (the vertical Chat layout is rect-only) makes the UI snap back. Guard: `ytLive.Tests/PropertiesHierarchyTests.cs`
 - **One list for the offered colours (TASK 60):** the border-colour drop-down builds its menu from
   `Models/BorderColorPalette.cs` (`NamedColor(Hex, Name)` + `NameOf(hex)` — **empty** for a colour