chore(aiwg): adopt shared BT6 maintainer workflow (#148)

* docs(policy): allow low-impact contributor courtesy cleanup

* chore(aiwg): migrate to shared BT6 maintainer plugin

* chore: reconcile delivery validation

.aiwg/plugins/bt6-maintainer/manifest.json

@@ -0,0 +1,32 @@
+{
+  "id": "bt6-maintainer",
+  "type": "plugin",
+  "name": "bt6-maintainer",
+  "version": "0.2.0",
+  "description": "Cross-repository maintenance and external-provider review for BT6 research and support tooling.",
+  "manifestVersion": "1",
+  "platforms": {
+    "claude": "full",
+    "codex": "full"
+  },
+  "keywords": [
+    "bt6",
+    "maintainer",
+    "research-tooling",
+    "support-tooling",
+    "pull-requests",
+    "issues",
+    "external-providers",
+    "trust-boundaries",
+    "merge-train",
+    "plugin",
+    "repository-operations"
+  ],
+  "deployment": {
+    "pathTemplate": ".{platform}/skills/{id}.md"
+  },
+  "pluginConfig": {
+    "payloadType": "addon",
+    "payloadPath": "payload/"
+  }
+}