Fix global slider reach + UI-scale font math + per-type grid spacing

resolvedCardHeight now picks the row's natural base (128 for WIDE /
episode aspect, 172 for TALL / poster aspect) via HomeRowViewOptions
.aspectRatio and selects the matching scaled global (cardHeightDp or
episodeCardHeightDp) from InterfaceCustomization. Previously the
function always passed HEIGHT_2X3_DP as the natural base, so every
row storing heightDp = HEIGHT_EPISODE = 128 hit the override branch
and the global Card slider silently skipped episode-aspect home rows
(Favorite-Episode preset, genreDefault rows, etc.).

MainContent and DisplaySizePage's preview Density no longer multiply
fontScale by the UI-scale factor. sp rendering pipes through
density * fontScale, so scaling both produced factor^2 text size -
slider 150% rendered fonts at 2.25x while layouts rendered at 1.5x.
Scaling density alone makes both linear; the user's system fontScale
stays applied on top.

ItemGrid, CollectionFolderGrid, CollectionMixedGrid, and HomeRowGrid
now honor the per-type viewOptions.spacing base (16/24/16 for the
three view-options presets) the same way CollectionFolderList already
did - scaled by the global Spacing percent at the consumer site.
Before this fix only the list-mode consumer honored the per-type base
and grids fell back to a fixed 16dp baseline regardless of preset.

Also wires ViewMoreCard's default size into cardHeightDp and
QueueRowOverlay's queue-thumbnail height into episodeCardHeightDp so
those two surfaces scale too. Adds a Why: comment on the
migrateLegacyRowSpacing clamp (50..150 per-row range, intentionally
narrower than the global 25..175). Drops a couple of restating //
comments in DisplaySizePage and imports java.util.EnumSet at the top
of InterfaceHelpersTest. New unit tests cover resolveCardHeight's
episode-natural-base path, per-row override precedence over the
global, and the linear-density invariant guarding against the
fontScale bug regressing.

app/src/main/java/com/github/damontecres/wholphin/MainContent.kt

@@ -68,7 +68,7 @@ fun MainContent(
                 val factor = interfaceCustomization.uiScalePercent / 100f
                 Density(
                     density = baseDensity.density * factor,
-                    fontScale = baseDensity.fontScale * factor,
+                    fontScale = baseDensity.fontScale,
                 )
             }
         CompositionLocalProvider(