Fix 4 Code Review findings on FRE-4928: dead heredoc, token warmup, summary path, .gitignore

- P2: Remove dead heredoc from run.sh mixed scenario
- P2: Add setup() warmup to seed real tokens for standalone scenarios
- P3: Replace handleSummary file output with --summary-export in run.sh
- P3: Add .gitignore for k6 results and .env
- Fix stray closing brace in scripts/load-test/lib/common.js

Co-Authored-By: Paperclip <noreply@paperclip.ing>

load-tests/darkwatch-auth/run.sh

@@ -31,20 +31,22 @@ echo ""
 case "$SCENARIO" in
   mixed)
     k6 run darkwatch-auth.js \
-      --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json" \
-      <<EOF
-EOF
+      --summary-export "$OUTPUT_DIR/summary-${TIMESTAMP}.json" \
+      --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
     ;;
   login)
     k6 run --scenario login_only darkwatch-auth.js \
+      --summary-export "$OUTPUT_DIR/summary-${TIMESTAMP}.json" \
       --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
     ;;
   logout)
     k6 run --scenario logout_only darkwatch-auth.js \
+      --summary-export "$OUTPUT_DIR/summary-${TIMESTAMP}.json" \
       --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
     ;;
   refresh)
     k6 run --scenario refresh_only darkwatch-auth.js \
+      --summary-export "$OUTPUT_DIR/summary-${TIMESTAMP}.json" \
       --out json="$OUTPUT_DIR/results-${TIMESTAMP}.json"
     ;;
   *)