test(session-snapshot): regenerate current rec-pin recording

The committed current rec-pin fixture held only request/header, so the corpus restore gate rejected it outside an open turn. Its owning scripted behavior already emits turn/start, step/start and the system surface message.

Regenerate the selected current fixture with ACP_SNAPSHOT_SPEC_BOOTSTRAP=1 and the focused rec-pin record test. Keep all retired parent and child generations unchanged. No parser, normalizer or production behavior changes.

Validation: the corpus restore test reproduced the missing-turn failure; documented owner bootstrap passed; pnpm exec vitest run packages/test-support/llm-replay/tests/session-format-corpus.spec.ts packages/test-support/session-snapshot/tests/suite.spec.ts passed (141 tests, one intentional skip).

packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-pin/session.v2.jsonl

@@ -1,2 +1,5 @@
-{"version":2,"isSeeded":false,"createdAt":0,"cwd":"{{cwd}}","delegationDepth":0,"type":"session","id":"{{session:1}}"}
+{"type":"session","version":2,"id":"{{session:1}}","createdAt":600,"cwd":"{{cwd}}","isSeeded":false,"delegationDepth":0}
+{"type":"turn/start","data":{"turn":1}}
+{"type":"step/start","data":{"turn":1,"step":1}}
+{"type":"system/message","data":{"turn":1,"step":1,"message":{"id":"{{message:1}}","role":"system","content":[{"type":"text","text":"{{system}}"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"}
 {"type":"request/header","data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":"{{tools}}"},"reason":"initial"}}