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/target.ts

@@ -7,7 +7,6 @@
  */
 
 import type { FileHandle } from 'node:fs/promises';
-import { Output } from './output';
 import * as nodeAlias from './node';
 import { assert, EventEmitter, FilePath, MaybePromise } from './misc';
 
@@ -39,7 +38,7 @@ export type TargetEvents = {
  */
 export abstract class Target extends EventEmitter<TargetEvents> {
 	/** @internal */
-	_output: Output | null = null;
+	_writerAcquired = false;
 
 	/** @internal */
 	_monotonicity: boolean | null = null; // null = unknown
@@ -582,6 +581,17 @@ export class StreamTarget extends Target {
 	}
 }
 
+/**
+ * This target writes to a `WritableStream<Uint8Array>`, meaning all writes are necessarily append-only and involve no
+ * seeking. Great for streaming data to a source that can only accept sequential data, like an HTTP server processing
+ * an incoming upload.
+ *
+ * Note that using this target *requires* that the underlying format write data sequentially. Not all formats do this,
+ * and this target will throw for the formats that don't. Check the guide for more.
+ *
+ * @group Output targets
+ * @public
+ */
 export class AppendOnlyStreamTarget extends Target {
 	/** @internal */
 	_writable: WritableStream<Uint8Array>;
@@ -787,7 +797,6 @@ export class RangedTarget extends Target {
 
 		this._baseTarget = baseTarget;
 		this._offset = offset;
-		this._output = baseTarget._output;
 	}
 
 	/** @internal */