fix: two long-running HLS transcode issues (#355)

* fix: release targets from Output._targets on finalize

Long-running HLS transcodes leak memory. Every finalized BufferTarget
stays in _targets until the outer Output closes, pinning its buffer.
Writer.finalize() already does this cleanup for writer-based flows;
extend it to buffer-finalize paths via the public 'finalized' event.

* fix: ReadOrchestrator LRU eviction picks only drained workers

assert(pendingSlices.length === 0) fires under heavy concurrent reads
(e.g. multi-rendition HLS decode from BlobSource). LRU filter only
checked !running; workers with queued slices could be evicted.
Add pendingSlices.length === 0 to the filter.

* fix: export AppendOnlyStreamTarget from index

Missing from the re-export; public docs import it by name.

* fix: join HLS init segment path with root + playlist path

Init path went through _getTarget bare; segments got joined with rootPath + playlist.path. Playlist-relative URI then can't resolve when the playlist lives in a subdirectory.

* Fix targets not being cleaned up, fix paused workers with remaining pending slices, modify doc block, fixed isRoot not being changed on proxied requests

---------

Co-authored-by: Vanilagy <[email protected]>

src/writer.ts

@@ -17,8 +17,13 @@ export class Writer {
 	private pos = 0;
 
 	constructor(target: Target, isMonotonic: boolean) {
+		if (target._writerAcquired) {
+			throw new Error('Can\'t have multiple Writers for the same Target.');
+		}
+
 		this.target = target;
 		target._setMonotonicity(isMonotonic);
+		target._writerAcquired = true;
 	}
 
 	start() {
@@ -55,10 +60,8 @@ export class Writer {
 	/** Called after muxing has finished. */
 	async finalize() {
 		assert(this.started && !this.finalized);
-		assert(this.target._output);
 
 		await this.target._finalize();
-		this.target._output._targets.delete(this.target);
 
 		this.finalized = true;
 	}