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/edit_and_feedback.js

@@ -0,0 +1,47 @@
+/**
+ * edit_and_feedback.js
+ *
+ * Enhances MkDocs Material docs pages by:
+ *
+ * 1. Adding a "Question? Give us feedback" link
+ *    below the "Edit" button.
+ *
+ *    - The link opens a GitHub issue with a template,
+ *      auto-filled with the current page URL and path.
+ *
+ * 2. Ensuring the edit button opens in a new tab
+ *    with target="_blank" and rel="noopener".
+ */
+document.addEventListener("DOMContentLoaded", function () {
+  const url = window.location.href;
+  const page = document.body.dataset.mdUrl || location.pathname;
+
+  const feedbackLink = document.createElement("a");
+  feedbackLink.href = `https://github.com/vllm-project/vllm/issues/new?template=100-documentation.yml&title=${encodeURIComponent(
+    `[Docs] Feedback for \`${page}\``
+  )}&body=${encodeURIComponent(`📄 **Reference:**\n${url}\n\n📝 **Feedback:**\n_Your response_`)}`;
+  feedbackLink.target = "_blank";
+  feedbackLink.rel = "noopener";
+  feedbackLink.title = "Provide feedback";
+  feedbackLink.className = "md-content__button";
+  feedbackLink.innerHTML = `
+  <svg
+    xmlns="http://www.w3.org/2000/svg"
+    height="24px"
+    viewBox="0 -960 960 960"
+    width="24px"
+    fill="currentColor"
+  >
+    <path d="M280-280h280v-80H280v80Zm0-160h400v-80H280v80Zm0-160h400v-80H280v80Zm-80 480q-33 0-56.5-23.5T120-200v-560q0-33 23.5-56.5T200-840h560q33 0 56.5 23.5T840-760v560q0 33-23.5 56.5T760-120H200Zm0-80h560v-560H200v560Zm0-560v560-560Z"/>
+  </svg>
+`;
+
+  const editButton = document.querySelector('.md-content__button[href*="edit"]');
+
+  if (editButton && editButton.parentNode) {
+    editButton.insertAdjacentElement("beforebegin", feedbackLink);
+
+    editButton.setAttribute("target", "_blank");
+    editButton.setAttribute("rel", "noopener");
+  }
+});