During onboarding the media drive is not mounted and ca.crt does not exist
yet (or still holds only a throwaway pre-drive state). The cert banner still
offered Download WROLPi Root CA, which 404'd. Gate the button and HTTPS
cert-setup banner on drive mounted, ca.crt present, and repair not running
so an existing CA on the drive can be served after mount/repair.
Introduce an onboarding system in the Controller that guides users
through selecting and mounting their primary media drive. This is
the fallback UI flow used when the main React app is unavailable.
Key changes:
- Add onboarding API endpoints and schemas (controller/api/onboarding.py)
- Add onboarding logic to detect drives, handle already-mounted drives
(needed for RPi which auto-mounts), and save primary drive selection
to the controller config when no mounts are configured
- Extend the Controller's index.html template with the onboarding UI
- Skip root cert creation until onboarding is complete
- Update first_startup.sh to support the onboarding/repair flow
- Add comprehensive tests for onboarding logic and API
