Adds build_aux_picker_rows() + format_aux_picker_entries() to
hermes_cli/inventory.py and converts both auxiliary-task pickers to them,
so custom providers, exclusions, and picker visibility can no longer be
dropped one call site at a time.
The two salvaged commits each fixed one kwarg at these same two sites
(user/custom providers, then for_picker). Both were per-site patches, so
the next aux picker would have reintroduced the gap. The seam makes the
correct behaviour the default a new caller cannot forget:
- user `providers:` and saved `custom_providers:` entries
- `model_catalog.excluded_providers`, matching /model
- exhausted-credential-pool providers stay visible
- only the active custom endpoint is probed, so an offline saved local
server can't hang the picker
- the virtual `moa` row is excluded (auxiliary_client unwraps it to the
aggregator anyway, so offering it is a silently-rewritten choice)
The vision picker also gains the current-selection marker it never had.
Also threads for_picker through build_models_payload, which had no way to
express it despite list_authenticated_providers supporting it.
