Follow-up to the #109930 salvage (#109901). The probe endpoint was the reported
site, but the same class covers every router path that expands a secondary
profile's `${VAR}` refs while only a home override is installed:
`GET /api/mcp/servers` (a `${VAR}` in `url` expanded from this process's env)
and the `/auth` config read, whose expanded entry is handed to the OAuth worker.
Hoist the PR's inline wrapper into one `_profile_secret_scope` context manager
(mirrors `_run_dashboard_mcp_oauth`'s wrapping) and use it at all three sites.
Policy unchanged: scope miss still falls through to os.environ outside
multiplexing; under multiplexing a miss is a miss, never another profile's value.
Tests: the salvaged probe test now uses monkeypatch.setenv (no raw os.environ
mutation); one invariant test for the list endpoint, red on origin/main.
teknium1
668f7278de