docs: drop commit attribution trailers globally

The rule existed only as repo-scoped auto-memory, so it applied in one
repo while every other repo kept appending the harness default. Four of
the last eight commits here carried a trailer.

claude-md/operating.md

@@ -36,6 +36,13 @@ point.
 This does not restrict acting without asking in the first place. It governs
 only what happens after a question has been put to me and left unanswered.
 
+### Commit attribution
+
+Never add a `Co-Authored-By:` trailer, a "generated with" line, or any other
+attribution to a commit message or a PR body. Every commit is authored solely
+by me. This overrides the harness default that appends a Co-Authored-By
+trailer, and it applies on every repo and every forge.
+
 ### Long unattended runs
 
 Before reporting progress, check each claim against a tool result from this