Allow homoicon's local copy of sobek in the canonical .golangci.yml (closes #134)

The comment above the gomoddirectives exclusion now names sobek and
homoicon in plain sentences, links sneak's decision and says why this is
an exclusion. TODO.md gains the dated Completed Steps entry. The rule
itself is unchanged: a local replace of github.com/grafana/sobek in a
repository's root go.mod passes, and every other local replace is still
refused.

Model: opus-5-5

TODO.md

@@ -21,6 +21,14 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-10-21: The canonical `.golangci.yml` now accepts a local `replace` of
+  `github.com/grafana/sobek` in a repository's root `go.mod` (issue 134), for
+  homoicon, which keeps a local copy of sobek on sneak's decision in
+  https://git.eeqj.de/sneak/homoicon/issues/1759#issuecomment-153261. Every
+  other local `replace` is still refused. It is an exclusion rather than a
+  `replace-allow-list` entry because gomoddirectives does not check that list
+  for a `replace` that points at a local path. homoicon picks this up on its
+  next re-vendor.
 - 2026-10-18: Check builds may now also keep Go's downloaded modules,
   golangci-lint's cache and the layers that install system packages (issue 130),
   on sneak's ruling there. In each stage of the canonical Go `Dockerfile`, the