INSCRIBED (ratingClassAlias) data layer and app-wide display follow-ups

[283375]

Context

Upstream songlist introduced ratingClassAlias: number on difficulty entries. So far it only appears as ratingClass: 3 + ratingClassAlias: 1.

UI-side support already landed on branch refactor/rating-class-selector:

• ArcaeaRatingClassDisplay (core/constants): maps (ratingClass, alias) to a display form; unknown (class, alias) combos fall back to the default form, so future upstream additions won't break anything.
• Theme: inscribed color.
• ArcaeaRatingClassSelector renders the BYD slot as INSCRIBED via RatingClassSelectorItem.display.

Tasks

1. DB: store rating_class_alias on difficulties

• Add a nullable rating_class_alias Int column to Difficulty, with a Room migration (ALTER TABLE ... ADD COLUMN). Old imports default to null (= no alias).
• If the Chart DatabaseView is still around by then, add d.rating_class_alias to its SELECT too; otherwise skip it (view is slated for deprecation).
• Files: core/src/main/kotlin/xyz/sevive/arcaeaoffline/core/database/entities/Difficulty.kt, core/src/main/kotlin/xyz/sevive/arcaeaoffline/core/database/ArcaeaOfflineDatabase.kt
• Search: @Entity(tableName = "difficulties"), Migration(

2. Parser: read ratingClassAlias from songlist

• Add val ratingClassAlias: Int? = null to the difficulty item and pass it through when building Difficulty.
• Files: core/src/main/kotlin/xyz/sevive/arcaeaoffline/core/database/externals/ArcaeaListDefinitions.kt (ArcaeaSonglistDifficultyItem), core/src/main/kotlin/xyz/sevive/arcaeaoffline/core/database/externals/importers/ArcaeaSonglistImporter.kt
• Search: class ArcaeaSonglistDifficultyItem, fun difficulties()

3. Selector: move item extension from Chart to Difficulty

• The transitional List<Chart>.toRatingClassSelectorItems() should become a List<Difficulty> version, feeding ratingClassAlias into ArcaeaRatingClassDisplay.of.
• Files: app/src/main/java/xyz/sevive/arcaeaoffline/ui/components/ArcaeaRatingClassSelector.kt (extension + transitional comment), call sites ArcaeaChartSelector.kt and UtilitiesCalculatorScreen.kt
• Search: toRatingClassSelectorItems

4. App-wide INSCRIBED-aware labels & colors

Currently INSCRIBED only affects the selector; everywhere else an INSCRIBED chart still shows "BEYOND":

• ArcaeaFormatters.ratingText builds e.g. "BEYOND 12.0" from ratingClass.toString() and is used by chart/play-result cards, B30/R30 lists, chart recommend, potential card, etc. Add an overload taking ArcaeaRatingClassDisplay (or an alias) and update callers.
• ArcaeaChartCard colors the difficulty label via ratingClassColor(ratingClass); switch to ratingClassColor(display).
• Search: ratingText(, ratingClass.toString(), ratingClassColor(ratingClass)

Notes

• DatabaseDeduplicatorViewModel uses ratingClass.toString() as a dedup key only — no change needed.
• The theme overhaul (seed-generated schemes via material-color-utilities, replacing the theme-builder exports in ui/theme/Colors.kt / ColorSchemes.kt) is future work and not part of this issue.

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This issue was filed by a coding agent (pi) at the owner's request, summarizing the discussion on branch refactor/rating-class-selector.