feat(discord): git verbs for the Discord Sage on the shared-signals root, seat identity through a package credential helper, vault record protocol (#1509)

Row 24. A writable root that is a git work tree may carry a git object in
the binding; the seat then has git_status, git_commit (explicit paths, seat
author, Requested-by trailer from the envelope requester, push at once per
D6), git_pull (ff-only) and git_push (one branch, never force), plus
reserve_id and per-write clone locks under protocol vault. Git children run
with no host config and one credential helper, bin/git-credential.mjs,
reading the 0600 seat token file named in the binding; the fleet helper
serves only the Gitea hosts. Suite 58/58, node 143. rev-code-02 APPROVED
round 1 (#1509 comment 26375, tree 82ab962f).

Co-Authored-By: Claude Fable 5.1 <[email protected]>

docs/TOOLS.md

@@ -189,7 +189,13 @@ roots, plus `write_file` and `edit_file` for roots marked `"write": true`
 credential shapes), and `web_fetch` and `web_search` when `tools.web`
 names a SearXNG instance (https only, public addresses only, three
 redirects, capped body, html to text), with each call in the turn record.
-Sage has no git; the operator commits from the terminal. `tools` is a fixed key: changing
+A writable root that is a git work tree may carry `git` (`branch`,
+`identity`, `tokenFile`, `author`, optional `protocol: "vault"`) and
+gains `git_status`, `git_commit` (explicit paths, seat author,
+`Requested-by:` trailer, push at once), `git_pull` (ff-only) and
+`git_push` (one branch, never force), with `reserve_id` under the vault
+protocol; git runs with no host config and the package's own credential
+helper reading a 0600 token file, never printed. `tools` is a fixed key: changing
 it needs a stop and start. Records
 under `<dataRoot>/discord/<binding>/`: `inbox.jsonl`, `outbox.jsonl`,
 `drops.jsonl`, `admissions.jsonl`, `notices.jsonl`, `reloads.jsonl`, write-once `turns/<id>.json`. Suite: