refactor: replace get_stream_url with get_source_uri per ADR-0002

Providers now expose a source URI (for FFmpeg) instead of a
viewer-facing stream URL. Playout Service will own transcoding.

- Add SourceUri value object (NetworkUrl | FilePath)
- Remove StreamQuality, StreamingProtocol from domain
- Simplify ProviderCapabilities (drop streaming_protocol, transcode)
- Jellyfin: return static direct stream URL
- Local files: return absolute file path
- Rename use case get_stream_url -> get_source
- Stream endpoint returns JSON SourceUri instead of 307 redirect

crates/presentation/src/handlers/schedule.rs

@@ -8,7 +8,7 @@ use api_types::{
     CurrentBroadcastResponse, ScheduleHistoryEntry, ScheduleResponse, SlotResponse,
 };
 use application::schedule::{
-    GenerateScheduleCommand, GetCurrentBroadcastQuery, GetEpgQuery, GetStreamUrlQuery,
+    GenerateScheduleCommand, GetCurrentBroadcastQuery, GetEpgQuery, GetSourceQuery,
 };
 use domain::value_objects::ChannelId;
 
@@ -70,13 +70,9 @@ pub async fn get_stream(
     State(state): State<AppState>,
     Path(id): Path<uuid::Uuid>,
 ) -> Result<axum::response::Response, AppError> {
-    let query = GetStreamUrlQuery { channel_id: id };
-    match application::schedule::get_stream_url::execute(&state.schedule_deps, query).await? {
-        Some(url) => Ok((
-            StatusCode::TEMPORARY_REDIRECT,
-            [("Location", url.as_str())],
-        )
-            .into_response()),
+    let query = GetSourceQuery { channel_id: id };
+    match application::schedule::get_source::execute(&state.schedule_deps, query).await? {
+        Some(uri) => Ok(Json(uri).into_response()),
         None => Ok(StatusCode::NO_CONTENT.into_response()),
     }
 }