Add worldwide genre style selector

docs/ARCHITECTURE.md

@@ -24,6 +24,7 @@ macOS App
 ├── Application Services
 │   ├── AI Director
 │   ├── Prompt Compiler
+│   ├── Genre & Style Catalog
 │   ├── Instrument Catalog
 │   ├── Arabic Pronunciation Processor
 │   ├── Project Versioning
@@ -109,3 +110,11 @@ the Suno Style Prompt.
 The current architecture does not include instrument images, audio
 previews, sound samples, playback, Freesound, an Instrument API or
 external API calls for instrument data.
+
+## Genre & Style Selector Boundary
+
+Genre and style catalog data is structured local data, separate from
+SwiftUI views. The Presentation layer may search, filter and toggle
+selections, while the catalog service owns stable ids, categories,
+optional regional metadata and search aliases. Selections are stored as
+existing `GenreStyle` values on the SongProject.