docs: pin cwd meaning in attribution footer

First dogfooding round stamped the build worktree instead of the session's
own working directory (the value the paired session id resolves to). Rule
now says so explicitly. Refs #11

AGENTS.md

@@ -38,7 +38,8 @@ with YAML frontmatter, spec at `omp-docs/references/okf-spec.md`).
   lands a tab in his Firefox; never make him hunt for it in Gitea.
 - **Attribution footer (issues and PRs)** — every issue or PR body you open ends
   with a `---` line, then `cwd: <working directory> · session: <omp session id>`
-  (session id from `/status`). Machine-made artifacts stay attributable to the
+  (session id from `/status`; `cwd` is that session's own working directory —
+  not the build checkout, when they differ). Machine-made artifacts stay attributable to the
   box and session that spawned them.
 - Releases: tag `vX.Y.Z` straight on `main` after verifying; tags are the deploy
   markers every other machine pulls to. Hotfixes are ordinary branches off the