test(deepseek): stop pinning Node's one-shot zstd decoder to the first frame

The frame-walking test asserted that zlib.zstdDecompressSync returns only the first of 40 concatenated frames. That was true when the walker was written, but nodejs/node#65865 (shipped in 26.10.0 and in 24.22.0 LTS) makes Node decode every frame, so the assertion fails on current Node 24 LTS and 26 while the walker itself is still correct. The assertion tested Node, not Codeman: the walker's own 40-frame checks stay, and the comments now say which Node versions stop at the first frame, since the supported range (>=22) still includes them.

test/deepseek-transcript.test.ts

@@ -4,10 +4,11 @@
  * Two of these assertions exist because the obvious implementation was measured
  * to be wrong against real files:
  *
- * - dsh appends ONE ZSTD FRAME PER WRITE, and Node's `zlib` zstd decoder stops
- *   at the first frame end. A 56-line transcript decoded as 1 line / 158 bytes,
- *   which reads as "the worker never answered" rather than as an error. The
- *   multi-frame fixtures below are the guard.
+ * - dsh appends ONE ZSTD FRAME PER WRITE, and Node's `zlib` zstd decoder
+ *   before 24.22 and 26.10 stops at the first frame end. A 56-line transcript
+ *   decoded as 1 line / 158 bytes, which reads as "the worker never answered"
+ *   rather than as an error. Newer Node decodes every frame (nodejs/node#65865),
+ *   so the multi-frame fixtures below pin the walker itself, not Node's decoder.
  * - a fresh worker in a case directory that had been used before answered its
  *   first `last-response` with the PREVIOUS session's reply. Session-to-
  *   transcript pairing is therefore its own describe block.
@@ -67,10 +68,6 @@ describe.skipIf(!zstdSupported())('zstd frame walking', () => {
     const lines = Array.from({ length: 40 }, (_, i) => JSON.stringify({ type: 'noise', seq: i }));
     const buf = framed(lines);
 
-    // The one-shot decoder is what this module had to replace.
-    const oneShot = (zlib as unknown as { zstdDecompressSync?: (b: Buffer) => Buffer }).zstdDecompressSync!(buf);
-    expect(oneShot.toString('utf8').trim().split('\n')).toHaveLength(1);
-
     expect(zstdFrameRanges(buf)).toHaveLength(40);
     expect(decodeZstdFrames(buf).trim().split('\n')).toHaveLength(40);
   });