Ship anonymized benchmark trace w600_r0.0015_st30 + provenance

Whitelist the sampled replay trace (1214 reqs / 274 sessions / ~600 s) past
the traces/ ignore so the repo is runnable without dash0 access. Metadata
only (token counts, opaque KV-block hashes, timing, session structure) — no
prompts/outputs/PII. traces/README documents schema, provenance (sampled
from the internal GLM-5.1 production trace via scripts/sample_trace.py), and
the regeneration command.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -3,7 +3,10 @@ __pycache__/
 .venv/
 *.egg-info/
 outputs/
-traces/
+traces/*
+# ship the anonymized sampled trace + its provenance (metadata only, no cleartext)
+!traces/w600_r0.0015_st30.jsonl
+!traces/README.md
 *.log
 .claude/
 # third_party/vllm tracked in git for patch management