Wire hf_token into HFCache httpx requests

[electron-rare]

Files: apps/api/src/kiki_cockpit/config.py:24, apps/api/src/kiki_cockpit/services/hf_cache.py:51-54

settings.hf_token is defined but HFCache.refresh()'s httpx client never sends Authorization: Bearer {token}. Private/gated HF models can't be fetched. Currently dead code.

Fix: pass token to HFCache.__init__ and conditionally add the Authorization header in refresh():

headers = {}
if self.hf_token:
    headers["Authorization"] = f"Bearer {self.hf_token}"
async with httpx.AsyncClient(**kwargs, headers=headers) as client:
    ...