One call-time resolver (env PORTFOLIO_SHARED_ROOT, default the in-repo
shared/) consumed by both MAF-side readers of the shared core:
persona._example_path() (the _EXAMPLE_PATH monkeypatch seam is kept) and
simulation._default_bundle_dir() (replaces the _BUNDLE_DIR module global).
De-risks the S4 extraction: re-pointing the commons becomes an env var,
not a code change. Override test proves the marker follows a tmp copy of
the whole shared tree; both detach points proven RED. Suite 155->157.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AaQCFnfsh3tfq1VfzdJpoi
