— the stage's id (e.g. "segmentation"). Used to
pick the right entry from options.overrides.
— the stage's built-in defaults; takes
effect for any knob not set by options.defaults
or options.overrides[stageId].
Optionaloptions: TIngestionLlmOptions— the caller's pipeline-level options surface.
May be undefined, in which case the resolver
returns internalDefault verbatim.
The merge is shallow per-field. A missing field at higher precedence does not blank out a lower-precedence value — it simply doesn't override.
Resolve the final per-stage LLM knobs.