refactor: rename core/transcode to core/stream, simplify MediaStreamer (#5166)

* refactor: rename core/transcode directory to core/stream

* refactor: update all imports from core/transcode to core/stream

* refactor: rename exported symbols to fit core/stream package name

* refactor: simplify MediaStreamer interface to single NewStream method

Remove the two-method interface (NewStream + DoStream) in favor of a
single NewStream(ctx, mf, req) method. Callers are now responsible for
fetching the MediaFile before calling NewStream. This removes the
implicit DB lookup from the streamer, making it a pure streaming
concern.

* refactor: update all callers from DoStream to NewStream

* chore: update wire_gen.go and stale comment for core/stream rename

* refactor: update wire command to handle GO_BUILD_TAGS correctly

Signed-off-by: Deluan <deluan@navidrome.org>

* fix: distinguish not-found from internal errors in public stream handler

* refactor: remove unused ID field from stream.Request

* refactor: simplify ResolveRequestFromToken to receive *model.MediaFile

Move MediaFile fetching responsibility to callers, making the method
focused on token validation and request resolution. Remove ErrMediaNotFound
(no longer produced). Update GetTranscodeStream handler to fetch the
media file before calling ResolveRequestFromToken.

* refactor: extend tokenTTL from 12 to 48 hours

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

Makefile

@@ -109,7 +109,7 @@ format: ##@Development Format code
 .PHONY: format
 
 wire: check_go_env ##@Development Update Dependency Injection
-	go tool wire gen -tags=$(GO_BUILD_TAGS) ./...
+	go tool wire gen -tags="$$(echo '$(GO_BUILD_TAGS)' | tr ',' ' ')" ./...
 .PHONY: wire
 
 gen: check_go_env ##@Development Run go generate for code generation