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

docs/maintainer-plugin.md

@@ -0,0 +1,47 @@
+# Shared BT6 Maintainer Plugin
+
+T3MP3ST consumes `bt6-maintainer` from the shared
+[`jmagly/bt6-aiwg-plugins`](https://github.com/jmagly/bt6-aiwg-plugins)
+repository. The public mirror is
+[`roctinam/bt6-aiwg-plugins`](https://git.integrolabs.net/roctinam/bt6-aiwg-plugins).
+
+The repository profile is `.aiwg/bt6-maintainer.yaml`. The release source,
+version, commit, and wrapper tree are pinned in
+`.aiwg/bt6-maintainer.lock.json`.
+
+## Verify the pinned release
+
+```bash
+npm run maintainer:check
+aiwg doctor --project-local
+```
+
+The check refreshes AIWG's Git package cache, verifies the pinned commit and Git
+tree, and compares the project wrapper byte-for-byte with the shared release.
+
+## Synchronize and deploy
+
+After intentionally updating the lock file to a reviewed shared release:
+
+```bash
+npm run maintainer:sync
+```
+
+The sync command uses `aiwg install` to fetch the external repository, verifies
+the immutable commit/tree, stages the wrapper, deploys it through `aiwg use` to
+Claude and Codex, rebuilds discovery, and runs the project-local doctor. The
+previous project-local wrapper is restored if deployment fails; rerun the sync
+to reconcile provider deployment artifacts after correcting the reported
+failure.
+
+AIWG issue [#1997](https://git.integrolabs.net/roctinam/aiwg/issues/1997)
+tracks direct discovery of nested standalone wrappers by `aiwg install`. Until
+that is resolved, the sync command bridges the cached repository to the
+project-local wrapper path. AIWG issues
+[#1996](https://git.integrolabs.net/roctinam/aiwg/issues/1996) and
+[#1998](https://git.integrolabs.net/roctinam/aiwg/issues/1998) track the legacy
+local-source installer crash and unsafe removal classification respectively.
+
+Do not restore `.aiwg/addons/t3mp3st-maintainer`; reusable maintainer behavior
+belongs in the shared repository, while T3MP3ST-specific commands and risk paths
+belong in the repository profile.