Add k6 load test scripts for Voiceprint verification endpoints (FRE-4930)

- k6 script with P99 latency thresholds (enrollment <500ms, verification <250ms, model retrieval <100ms)
- Configurable 500 req/s sustained throughput for 5 minutes
- Mixed workload scenario + individual endpoint scenarios
- GitHub Actions workflow for automated load testing
- Runner script with environment configuration
- JSON result export for CI artifact collection
- .gitignore entry for load test results

load-tests/voiceprint/run.sh

@@ -0,0 +1,69 @@
+#!/usr/bin/env bash
+# Run k6 load tests for Voiceprint endpoints
+# Usage: ./run.sh [scenario]
+#   scenario: mixed (default), enrollment, verification, model-retrieval
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+# Load environment variables from .env if present
+if [[ -f .env ]]; then
+  set -a
+  source .env
+  set +a
+fi
+
+SCENARIO="${1:-mixed}"
+OUTPUT_DIR="${SCRIPT_DIR}/results"
+TIMESTAMP="$(date +%Y%m%d-%H%M%S)"
+
+mkdir -p "$OUTPUT_DIR"
+
+echo "=== Voiceprint Load Test ==="
+echo "Scenario: $SCENARIO"
+echo "Target RPS: ${TARGET_RPS:-500}"
+echo "Duration: ${DURATION:-300s}"
+echo "Base URL: ${VOICEPRINT_BASE_URL:-http://localhost:3000}"
+echo ""
+
+case "$SCENARIO" in
+  mixed)
+    k6 run voiceprint.js \
+      --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json" \
+      <<EOF
+EOF
+    ;;
+  enrollment)
+    k6 run --scenario enrollment_only voiceprint.js \
+      --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
+    ;;
+  verification)
+    k6 run --scenario verification_only voiceprint.js \
+      --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
+    ;;
+  model-retrieval)
+    k6 run --scenario model_retrieval_only voiceprint.js \
+      --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
+    ;;
+  *)
+    echo "Unknown scenario: $SCENARIO"
+    echo "Available: mixed, enrollment, verification, model-retrieval"
+    exit 1
+    ;;
+esac
+
+EXIT_CODE=$?
+
+if [[ $EXIT_CODE -eq 0 ]]; then
+  echo ""
+  echo "✅ All thresholds passed!"
+  echo "Results saved to: $OUTPUT_DIR/results-${TIMESTAMP}.json"
+else
+  echo ""
+  echo "❌ Thresholds failed. Check output above."
+  echo "Results saved to: $OUTPUT_DIR/results-${TIMESTAMP}.json"
+fi
+
+exit $EXIT_CODE