The terminal `hermes model` wizard (_model_flow_named_custom) always
live-probed a custom provider's /models endpoint, ignoring the configured
`models:` list. For plans whose endpoint exposes a large catalog (e.g. Baidu
Qianfan Coding Plan returns 100+ models for a 2-3 model plan) the picker
flooded with models the user can't use.
This wires `discover_models` (and the `models:` list) through
_named_custom_provider_map into the flow and honors `discover_models: false`
the same way the slash-command picker (model_switch.py sections 3 & 4) does:
- Default stays True — live probe, no behaviour change.
- discover_models: false → use the configured `models:` list verbatim,
skip the probe (string 'false'/'no'/'0' normalised to False).
- If the probe is on but returns empty, fall back to the configured list
instead of forcing manual entry.
Closes#18726
kshitijk4poor
7ae8aac3b9