sgl-router: experimental Rust HTTP router for SGLang worker pools (#25851)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

experimental/sgl-router/tests/e2e/k8s_integration/manifests/rbac.yaml

@@ -0,0 +1,34 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: sgl-router
+  namespace: sgl-router-test
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: sgl-router
+  namespace: sgl-router-test
+rules:
+  # EndpointSlice watch (k8s discovery backend)
+  - apiGroups: ["discovery.k8s.io"]
+    resources: ["endpointslices"]
+    verbs: ["get", "list", "watch"]
+  # Service list/watch (needed to resolve EndpointSlice owner)
+  - apiGroups: [""]
+    resources: ["services", "pods"]
+    verbs: ["get", "list", "watch"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: sgl-router
+  namespace: sgl-router-test
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: sgl-router
+subjects:
+  - kind: ServiceAccount
+    name: sgl-router
+    namespace: sgl-router-test