Add vLLM v0.18.1 source tree with KV transfer abort fix

third_party/vllm/ now tracked in git for direct patch management.
Based on vLLM v0.18.1 release with one patch applied:

  vllm/v1/core/sched/scheduler.py:
    Replace fatal assert with graceful skip when KV transfer callback
    arrives for an already-aborted request during PD disaggregated serving.

Future vLLM modifications should be made directly in third_party/vllm/
and committed normally. The patches/ directory is kept as documentation
of what changed from upstream.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

third_party/vllm/examples/online_serving/dashboards/grafana/README.md

@@ -0,0 +1,59 @@
+# Grafana Dashboards for vLLM Monitoring
+
+This directory contains Grafana dashboard configurations (as JSON) designed to monitor
+vLLM performance and metrics.
+
+## Requirements
+
+- Grafana 8.0+
+- Prometheus data source configured in Grafana
+- vLLM deployment with Prometheus metrics enabled
+
+## Dashboard Descriptions
+
+- **performance_statistics.json**: Tracks performance metrics including latency and
+  throughput for your vLLM service.
+- **query_statistics.json**: Tracks query performance, request volume, and key
+  performance indicators for your vLLM service.
+
+## Deployment Options
+
+### Manual Import (Recommended)
+
+The easiest way to use these dashboards is to manually import the JSON configurations
+directly into your Grafana instance:
+
+1. Navigate to your Grafana instance
+2. Click the '+' icon in the sidebar
+3. Select 'Import'
+4. Copy and paste the JSON content from the dashboard files, or upload the JSON files
+   directly
+
+### Grafana Operator
+
+If you're using the [Grafana Operator](https://github.com/grafana-operator/grafana-operator)
+in Kubernetes, you can wrap these JSON configurations in a `GrafanaDashboard` custom
+resource:
+
+```yaml
+# Note: Adjust the instanceSelector to match your Grafana instance's labels
+# You can check with: kubectl get grafana -o yaml
+apiVersion: grafana.integreatly.org/v1beta1
+kind: GrafanaDashboard
+metadata:
+  name: vllm-performance-dashboard
+spec:
+  instanceSelector:
+    matchLabels:
+      dashboards: grafana  # Adjust to match your Grafana instance labels
+  folder: "vLLM Monitoring"
+  json: |
+    # Replace this comment with the complete JSON content from
+    # performance_statistics.json - The JSON should start with { and end with }
+```
+
+Then apply to your cluster:
+
+```bash
+kubectl apply -f your-dashboard.yaml -n <namespace>
+```