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/docs/mkdocs/javascript/run_llm_widget.js

@@ -0,0 +1,19 @@
+// Add RunLLM widget
+document.addEventListener("DOMContentLoaded", function () {
+    var script = document.createElement("script");
+    script.type = "module";
+    script.id = "runllm-widget-script"
+  
+    script.src = "https://widget.runllm.com";
+  
+    script.setAttribute("version", "stable");
+    script.setAttribute("runllm-keyboard-shortcut", "Mod+j"); // cmd-j or ctrl-j to open the widget.
+    script.setAttribute("runllm-name", "vLLM");
+    script.setAttribute("runllm-position", "BOTTOM_RIGHT");
+    script.setAttribute("runllm-position-y", "120px");
+    script.setAttribute("runllm-position-x", "20px");
+    script.setAttribute("runllm-assistant-id", "207");
+  
+    script.async = true;
+    document.head.appendChild(script);
+  });