kill LibraryItem, unify to MediaItem; decouple schedule engine from providers

ADR-0001: MediaItem absorbs LibraryItem fields (provider_id, external_id,
collection_name, collection_type, synced_at, role/MediaRole).
LibraryItem + LibraryItemRow deleted. All ports/adapters/tests updated.

ADR-0002: schedule engine takes LibraryQuery instead of IProviderRegistry.
Algorithmic blocks query library via search(), manual blocks via get_by_id().
get_stream_url removed from engine; provider_registry moved to ScheduleDeps
for playback-time stream URL resolution in application layer.

BlockContent provider_id field removed (meaningless when querying library).

crates/mcp/src/main.rs

@@ -48,7 +48,7 @@ async fn main() -> anyhow::Result<()> {
     let event_publisher: Arc<dyn domain::ports::EventPublisher> = event_bus.clone();
 
     let schedule_engine = Arc::new(ScheduleEngineService::new(
-        provider_registry.clone(),
+        wire.library_query.clone(),
         wire.channel_query.clone(),
         wire.schedule_query.clone(),
         wire.schedule_command.clone(),
@@ -70,6 +70,7 @@ async fn main() -> anyhow::Result<()> {
         schedule_query: wire.schedule_query.clone(),
         schedule_command: wire.schedule_command.clone(),
         event_publisher: event_publisher.clone(),
+        provider_registry: provider_registry.clone(),
     });
 
     let library_query_deps = Arc::new(application::library::LibraryQueryDeps {

crates/mcp/src/server.rs

@@ -171,7 +171,7 @@ impl KTvMcpServer {
     }
 
     #[tool(
-        description = "Search media items. content_type: movie|episode|short. Returns JSON array of LibraryItem."
+        description = "Search media items. content_type: movie|episode|short. Returns JSON array of MediaItem."
     )]
     async fn search_media(&self, #[tool(aggr)] p: SearchMediaParams) -> String {
         library::search_media(

crates/mcp/src/tools/library.rs

@@ -102,7 +102,7 @@ pub async fn search_media(
             let dtos: Vec<LibraryItemDto> = items
                 .into_iter()
                 .map(|i| LibraryItemDto {
-                    id: i.id().to_string(),
+                    id: i.id().value().to_string(),
                     provider_id: i.provider_id().to_string(),
                     external_id: i.external_id().to_string(),
                     title: i.title().to_string(),