Playground completions (chat streaming via ``fetchChunkedData``)
and the raw ``fetch()`` calls for image / audio generation skip
umi's ``request`` pipeline and so miss the request interceptor in
``request.extensions.ts`` that pins tenant context. Higress
receives those calls without ``X-Organization-Id`` and the auth
callback falls back to the user's USER-principal id rather than
their active Org, which makes Playground usage invisible from
Org-scoped Usage views even after the backend learned to backfill
``consumer_principal_id``.
Centralise the lookup in ``tenantHeaders()`` next to
``fetchChunkedData`` so both streaming helpers and the four
``fetch()``-direct entry points in ``playground/apis/index.ts``
(image / TTS) attach the header with the same precedence as the
umi interceptor (``createScopeOrgOverride`` first,
``currentOrganizationId`` second). Returns an empty object when
no active org context is set, leaving requests unchanged.
