Two QA-reported bugs on the "Open in Playground" path. Both come
down to the model id the playground submits not matching what
``/v1/models`` / the dispatcher key off:
* Routes page (OSS UI) emitted ``default/<name>`` for routes in the
platform Org and 404'd. ``use-open-playground`` keyed off the
``is_platform`` flag alone; stale caches that drop the flag
slipped through. Also accept the well-known ``name === 'default'``
(``PLATFORM_PRINCIPAL_NAME`` on the backend) as a fallback signal.
* My Models page (enterprise UI, non-admin) emitted bare ``<name>``
with no Org prefix for non-platform routes. Use ``model.name``
from ``/v2/my-models`` verbatim — the backend ("fix: principal
prefix in my-models") now rewrites that field to the OpenAI-style
id server-side, which also closes the cross-Org grant gap a
client-side cache lookup can't (the granting Org isn't in the
caller's member list). Card title now shows the prefixed id, so
users can tell apart same-named models from different Orgs.
Routes page keeps ``useOpenPlayground`` — that surface is always
scoped to the caller's own Org, the local cache is sufficient, and
``/model-routes`` still returns the raw ``name``.
Also drops the now-unused ``onClick`` prop on ``ModelItem``: the
card had ``clickable={false}`` so the parent-passed handler was
already dead code; the Button drives the playground navigation.
