chore: ignore the local module overlay files

go.local.mod carries a `replace` directive pointing at a sibling checkout
so rho can be tested against local flux changes. It must never be committed:
CI runs with no overlay and builds against the pinned published module, and a
committed replace would silently override it. The files were showing as
untracked in every checkout.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Patel230

.gitignore

@@ -62,3 +62,9 @@ rho-sec105b.log
 # `gitnexus analyze` regenerates a root CLAUDE.md that would shadow AGENTS.md
 # for tools that prefer it; keep the regenerated copy out of git.
 /CLAUDE.md
+
+# Local module overlay for building against a sibling checkout (e.g. flux).
+# go.local.mod carries a `replace` directive pointing at ../<repo>; committing
+# it would break CI, which builds against the pinned published module.
+/go.local.mod
+/go.local.sum