docs: GST-985 changelog fragment and troubleshooting note

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

changelog.d/gst-985-review-bind-scratch.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- **A test lane's scratch folder no longer breaks the /ship review bind.** When an untracked `.review-units-test-*/` folder appeared or vanished while reviewers ran, Step 11.5 saw a different tree and the only repair was rerunning Steps 9 to 11.5 (about 20M tokens). Review records now fingerprint with `gstack-wtree --review`, which leaves out root dot-folders that hold no tracked file. `.github/` and `.gstack/` always count, and any change to a tracked file still breaks the bind. The pregate, test evidence and every other caller keep the whole tree. (GST-985)

docs/troubleshooting.md

@@ -570,6 +570,9 @@ the base has moved.
 **Meaning.** The working tree changed between the pass's `gstack-review-log --start` and
 its logged row: an edit, commit or merge landed while reviewers were still reading. The
 reviewers may not have seen that change, so the row's `review_binding.state` is `changed`.
+Review records fingerprint with `gstack-wtree --review`, which skips untracked root dot-folders
+that hold no tracked file (never `.github/` or `.gstack/`), so a test lane's scratch folder alone
+does not move the tree.
 Step 11.5 cannot bind it and inserts `9 → 10 → 11 → 11.5`. Logging the same results again
 cannot repair it.