feat(autoload): list Ideogram-4 + Qwen-Image-Layered precision configs in the auto-loader

The two config-only series (precision-config/ only, no weights) are now registered
for resource discovery so the Precision Config Auto Loader dropdown auto-lists their
configs and resolves a selection back to the full series id — exactly like the
existing full-model series. They are deliberately kept OUT of the model-download
`model_series` dropdown (nothing to download there).

- add _PRECISION_CONFIG_ONLY_SERIES + _ALL_RESOURCE_SERIES (= MODEL_SERIES_LIST + them)
- point discovery/resolution (_build_dropdown, _refresh_all_caches, _resolve_selection,
  resolve_selection_no_series) at the union; nodes.py model_series dropdowns keep
  MODEL_SERIES_LIST unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>