Add language catalog selector

docs/ARCHITECTURE.md

@@ -27,6 +27,7 @@ macOS App
 │   ├── Genre & Style Catalog
 │   ├── Instrument Catalog
 │   ├── Vocalist Catalog
+│   ├── Language Catalog
 │   ├── Arabic Pronunciation Processor
 │   ├── Project Versioning
 │   └── Validation
@@ -126,3 +127,10 @@ Vocalist presets are local structured data, separate from SwiftUI views.
 The catalog service supplies stable ids and preset metadata, while the
 Presentation layer searches and toggles the corresponding `Vocalist`
 values on the SongProject.
+
+## Language Selector Boundary
+
+Language catalog data is local structured data, separate from SwiftUI
+views. The catalog service owns stable ids, regional categories and
+search terms; the Presentation layer toggles the corresponding
+`LanguageSelection` values on the SongProject.

docs/DATA_MODEL.md

@@ -60,6 +60,13 @@ VocalistPreset
 - aliases[]
 - searchTerms[]
 
+LanguageCatalogItem
+- id
+- name
+- familyCategory
+- aliases[]
+- searchTerms[]
+
 SongSection
 - id
 - type (intro, verse, preChorus, chorus, bridge, outro, custom)

docs/OPEN_QUESTIONS.md

@@ -12,7 +12,9 @@ finalized.
 -   Complete worldwide instrument catalog taxonomy, family/category
     groups, region/origin coverage, aliases/search terms and maintenance
     strategy.
--   Exact list of supported languages/dialects for MVP.
+-   Resolved: languages use a large curated local catalog with category
+    browsing, search aliases and checkbox multi-select. Exact dialect
+    preset coverage remains to be defined.
 -   Arabic diacritization policy: full tashkeel vs
     pronunciation-targeted tashkeel.
 -   External music-generation handoff is not in the current scope.

docs/PRODUCT.md

@@ -41,6 +41,8 @@ and writing engine, then prepares final lyrics and style instructions.
 -   User controls vocal gender/type, rap/singing mode, delivery and
     section-specific performance.
 -   Multiple languages and dialects can be used in one song.
+-   Languages can be selected from a large local catalog with search,
+    category browsing and checkbox multi-select.
 -   Arabic receives dedicated diacritics/harakat/tanween handling for
     pronunciation.
 -   Energy and emotional progression can change throughout the song.
@@ -94,6 +96,13 @@ presets. Users can search, browse by category and select or deselect
 multiple vocalists with checkboxes. Each preset supplies a role label,
 voice type, gender selection and performance style for the Song Project.
 
+## Language Selector
+
+The application provides a large curated local language catalog. Users
+can search, browse by regional category and select or deselect multiple
+languages with checkboxes. Removing a language also removes any dialect
+entries attached to it from the Song Project.
+
 ## Project Management
 
 Every song is stored as a project. Important changes can create versions

docs/TASKS.md

@@ -133,3 +133,4 @@ lyrics and style prompt in the project.
 -   [x] Add confirmed project deletion from the project browser.
 -   [x] Add a worldwide genre and style selector with checkbox multi-select.
 -   [x] Add a vocalist preset selector with checkbox multi-select.
+-   [x] Add a language selector with checkbox multi-select.