MediaRole auto-detection + manual role API + sync wiring (#7)

role_detector: classify items as Interstitial by collection name/tag patterns.
Wire chapter extraction + role detection into sync adapter (worker + presentation).
SQLite: persist/read role column, migration.
PUT /library/items/{id}/role endpoint for manual override.

crates/domain/src/ports/library.rs

@@ -5,7 +5,7 @@ use crate::models::{
     LibraryCollection, LibrarySyncLogEntry, LibrarySyncResult, MediaItem,
     SeasonSummary, ShowSummary,
 };
-use crate::value_objects::{ContentType, LibrarySearchFilter};
+use crate::value_objects::{ContentType, LibrarySearchFilter, MediaRole};
 
 use super::media::IMediaProvider;
 
@@ -18,6 +18,8 @@ pub trait LibraryCommand: Send + Sync {
     async fn log_sync_start(&self, provider_id: &str) -> DomainResult<i64>;
 
     async fn log_sync_finish(&self, log_id: i64, result: &LibrarySyncResult) -> DomainResult<()>;
+
+    async fn update_role(&self, item_id: &str, role: MediaRole) -> DomainResult<()>;
 }
 
 #[async_trait]