Refactor load testing scripts to support Bash and PowerShell

- Updated README.md to reflect changes in load testing commands and added usage examples for Bash scripts.
- Converted PowerShell load testing scripts to Bash equivalents for better cross-platform compatibility.
- Added new Bash scripts: run-loadtests.sh, summarize-artillery.sh, and summarize-k6.sh to mirror existing PowerShell functionality.
- Updated admin-api.js and ws-chat.yml for consistency and improved performance metrics reporting.
- Enhanced error handling and output formatting in summary scripts for better readability.

scripts/loadtest/summarize-artillery.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+# summarize-artillery.sh — Extract counters, rates and percentile stats from an
+# Artillery JSON report. Mirrors scripts/loadtest/summarize-artillery.ps1.
+# Usage: ./scripts/loadtest/summarize-artillery.sh <artillery-report.json>
+set -euo pipefail
+
+if [[ $# -lt 1 ]]; then
+  echo "Usage: $0 <artillery-report.json>" >&2
+  exit 2
+fi
+report_file="$1"
+[[ -f "$report_file" ]] || { echo "Report file not found: $report_file" >&2; exit 1; }
+
+REPORT_FILE="$report_file" node <<'EOF'
+const fs = require('fs');
+const report = JSON.parse(fs.readFileSync(process.env.REPORT_FILE, 'utf8'));
+const aggregate = report.aggregate;
+if (!aggregate) throw new Error('Artillery report is missing aggregate data.');
+
+const get = (obj, name) => (obj && obj[name] !== undefined) ? obj[name] : undefined;
+const counters = aggregate.counters || {};
+const rates = aggregate.rates || {};
+const summaries = aggregate.summaries || {};
+
+const created = Number(get(counters, 'vusers.created') || 0);
+const failed = Number(get(counters, 'vusers.failed') || 0);
+const completed = Number(get(counters, 'vusers.completed') || 0);
+const errorRate = created > 0 ? +((failed / created) * 100).toFixed(2) : 0;
+
+console.log('=== Artillery WebSocket Summary ===');
+console.log(`source: ${process.env.REPORT_FILE}`);
+if (report.timestamp) console.log(`timestamp: ${report.timestamp}`);
+console.log(`vusers.created: ${created}`);
+console.log(`vusers.completed: ${completed}`);
+console.log(`vusers.failed: ${failed}`);
+console.log(`vusers.failure_rate_percent: ${errorRate}`);
+
+for (const metric of ['ws.messages_sent', 'ws.messages_received', 'ws.ping', 'plugins.metrics-by-endpoint.response_time']) {
+  const v = get(counters, metric);
+  if (v !== undefined) console.log(`${metric}: ${v}`);
+}
+for (const [k, v] of Object.entries(rates || {})) console.log(`rate.${k}: ${v}`);
+
+const fmt = (prefix, stats) => {
+  if (!stats) return;
+  const parts = [];
+  for (const name of ['count', 'min', 'max', 'mean', 'median', 'p95', 'p99']) {
+    const v = get(stats, name);
+    if (v !== undefined) parts.push(`${name}=${v}`);
+  }
+  if (parts.length) console.log(`${prefix}: ${parts.join(', ')}`);
+};
+for (const [k, v] of Object.entries(summaries)) fmt(`summary.${k}`, v);
+EOF