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/.env.example

@@ -0,0 +1,19 @@
+# Voiceprint Load Test Configuration
+# Copy to .env and adjust values
+
+# Base URL of the Voiceprint API
+VOICEPRINT_BASE_URL=http://localhost:3000
+
+# API authentication token
+API_TOKEN=test-token
+
+# Test duration (default: 300s = 5 minutes)
+DURATION=300s
+
+# Target requests per second (default: 500)
+TARGET_RPS=500
+
+# P99 latency thresholds in milliseconds
+ENROLLMENT_P99_MS=500
+VERIFICATION_P99_MS=250
+MODEL_RETRIEVAL_P99_MS=100