Persist selections and compile song output

docs/TASKS.md

@@ -86,8 +86,8 @@ requirement is missing and blocks implementation, record it in
 -   [x] Add browsing/filtering by family/category.
 -   [x] Add browsing/filtering by region/origin where useful.
 -   [x] Add checkbox-based multi-select and deselect behavior.
--   [ ] Persist selected instruments on the current Song Project.
--   [ ] Make selected instruments available to OpenAI/song-generation
+-   [x] Persist selected instruments on the current Song Project.
+-   [x] Make selected instruments available to OpenAI/song-generation
     logic for arrangement, roles, entry/exit timing, relevant structure
     decisions and Suno Style Prompt generation.
 -   [x] Preserve existing Manual/Auto arrangement behavior.
@@ -96,7 +96,7 @@ requirement is missing and blocks implementation, record it in
 
 ## Phase 7 --- Prompt Compiler
 
--   [ ] Create deterministic compiler from approved SongProject → Suno
+-   [x] Create deterministic compiler from approved SongProject → Suno
     output.
 -   [ ] Generate lyrics text with section/performance directives where
     appropriate.