Promote raw stream replay into standalone simulator tool and add SSE field doc

tests/scripts/run-raw-stream-sim.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "$0")/../.." && pwd)"
+cd "$ROOT_DIR"
+
+REPORT_DIR="artifacts/raw-stream-sim"
+mkdir -p "$REPORT_DIR"
+REPORT_PATH="$REPORT_DIR/report-$(date -u +%Y%m%dT%H%M%SZ).json"
+
+node tests/tools/deepseek-sse-simulator.mjs \
+  --samples-root tests/raw_stream_samples \
+  --report "$REPORT_PATH" \
+  "$@"
+
+echo "[run-raw-stream-sim] report: $REPORT_PATH"