docs: complete the remaining 15 dependent compatibility audits

Process the remaining current declared `GitPython` consumers in the September
2026 top-15,000 PyPI download snapshot, bringing the four audit batches to 115
distinct projects. Each dependent has a separate agent assignment and verified
release archive. Record released caller identity, import proofs, commands,
environments, baseline comparisons, coverage limits and retained evidence in
`test/downstream/audit-2026-10-23-batch-4.md` and its JSON manifest, and link them
from the downstream README.

Both local CLI and Gix selections finish with 117 unchanged upstream passes,
187 real supplemental passes, one failure and two upstream Jira skips. The
Dstack nested-default-branch failure also occurs with released `GitPython`
3.2.1, so no production compatibility fix is justified. MkNotebooks also passes
its separate unchanged upstream Binder example build on both backends and the
released baseline. Earlier index-writer, constructor-subclass and empty-config
section breaks remain open.

The completed inventory covers all identified ranked declared-consumer download
weight (348,530,835 monthly requests, including extras), rather than attributing
`GitPython` installations or unique users. Preserve limitations for missing
metadata, lower-ranked/historical/undeclared users, isolated helper ASTs, mocked
upstream cases, omitted application stacks and retained Git CLI fallbacks.

Validation rechecks all 15 release archive hashes, 115-project distinctness,
backend result parity, result XML/import proofs, weight totals, JSON and local
Markdown links; `git diff --check` passes. No production code changed, so the
manifest accurately references the preceding final full suites after
`549db56d` instead of claiming new runs. Sources, environments and logs remain
in ignored audit caches. This commit is local only.

Author: codex

test/downstream/README.md

@@ -19,6 +19,13 @@ archives, commands, import proofs and coverage limits. Additional selections are
 popularity-ranked; the original known-user additions mean this is a 100-project
 audit rather than a strict mathematical top 100.
 
+The [remaining 15-project batch](audit-2026-10-23-batch-4.md) brings the audit to
+115 distinct projects and completes every identified current declared consumer
+in the September snapshot of the top 15,000 distributions. Its
+[manifest](audit-2026-10-23-batch-4.json) records released callers, tests, baseline
+comparisons and limits. This covers the identified distribution download weight;
+it does not attribute GitPython installs or imply complete application coverage.
+
 Run released projects' GitPython-related tests against this checkout with
 [uv](https://docs.astral.sh/uv/) and Git 2.52 or newer: