Android: Material3 components render with default M3 surface colors instead of theme tokens

[DatScreamer]

Summary

Android's LitterAppTheme (apps/android/app/src/main/java/com/litter/android/ui/LitterTheme.kt) only maps 11 of the 36 Material3 color roles when building the ColorScheme. Every Material3 component that reads the remaining roles — ModalBottomSheet (60 uses), AlertDialog (31), OutlinedTextField (54), FilterChip (25), Switch (31), Slider (14), Card (50), Badge (50) — falls back to the baseline Material Design 3 surface palette (the stock purple-tinted surfaces) instead of the Litter theme tokens.

iOS is unaffected because SwiftUI views consume the LitterTheme tokens directly; there is no Material role layer to leave unset.

Why

The color scheme is built like this:

darkColorScheme(
    primary = activeTheme.accentStrong,
    onPrimary = activeTheme.textOnAccent,
    secondary = activeTheme.textSecondary,
    onSecondary = activeTheme.textPrimary,
    background = activeTheme.background,
    onBackground = activeTheme.textBody,
    surface = activeTheme.surface,
    onSurface = activeTheme.textBody,
    error = activeTheme.danger,
    onError = activeTheme.textOnAccent,
    outline = activeTheme.border,
)

The other 25 roles (surfaceVariant, onSurfaceVariant, surfaceContainer*, outlineVariant, primaryContainer, secondaryContainer, tertiary*, errorContainer, inverse*, scrim) stay at darkColorScheme()/lightColorScheme() defaults, so Material3 components render the stock M3 surfaces.

Fix

Derive the full 36-role scheme from the existing Litter tokens using Google's official material-color-utilities (the engine behind the Material Theme Builder) as a build-time generator. See PR #312.