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.

docs/MONITORING.md

@@ -52,7 +52,7 @@ Config: `monitoring/prometheus/prometheus.yml` (15s scrape interval)
 - **Linear Void app**: `monitoring/grafana/dashboard.json` — clients, messages, moderation, Redis, sessions, scrape health
 - **Prometheus ops**: `monitoring/grafana/dashboards/dashboard.json` — TSDB, CPU/memory, WAL, compactions, query latency
 
-## Metrics checking
+## Metrics Checking
 
 See detailed scripts for querying Prometheus scrape targets:
 
@@ -78,21 +78,13 @@ See detailed scripts for querying Prometheus scrape targets:
 | Prometheus targets down | Check container network: all must be on `linearvoid-net`             |
 | Alert not firing        | Check Prometheus → Alerts tab, verify `rule_files` in prometheus.yml |
 
-### Grafana shows no data
+**Grafana no data**: ensure datasource points to `http://prometheus:9090`; confirm Prometheus is healthy; check dashboard query labels match active jobs.
 
-- Ensure datasource points to <http://prometheus:9090>.
-- Confirm Prometheus is healthy.
-- Check dashboard query labels match active jobs.
-
-### High cardinality or query slowness
-
-- Reduce unneeded labels.
-- Limit expensive dashboard panels.
-- Tune retention and query windows.
+**High cardinality / slow queries**: reduce unneeded labels; limit expensive panels; tune retention and query windows.
 
 ## Operational Recommendations
 
 - Keep alert thresholds tied to actual user impact.
 - Review dashboards after each release that changes endpoints or metrics names.
 - Periodically test alert routing and incident response flow.
-- Metrics retention is set to **30 days** time-based plus a **15GB** size cap (`--storage.tsdb.retention.time=30d --storage.tsdb.retention.size=15GB` on the `prometheus` service in `docker-compose.yml` and `docker-compose.prod.yml`). Increase the size cap before extending the time window so the TSDB does not hit the disk limit first.
+- Retention: **30 days** time-based plus **15GB** size cap (`--storage.tsdb.retention.time=30d --storage.tsdb.retention.size=15GB` on the `prometheus` service in `docker-compose.yml` and `docker-compose.prod.yml`). Increase the size cap before extending the time window so the TSDB does not hit the disk limit first.