Profiles previously had no validation, so config errors surfaced far
from their origin and cryptically:
- explicit profile missing `model` fell back to the profile NAME as the
model (a profile named "local" would send "model": "local")
- default profile missing `model` with no model param produced
"model": null -> API 400
- missing `api_url` surfaced as requests InvalidURL
_resolve_model_profile now runs _validate_profile (dict type + api_url)
before reading fields and _require_model on the effective model,
raising ValueErrors that name the profile, the missing field, and the
config.json path to fix. Bare model names still legally substitute for
a default profile's missing model field.
Tests: new TestH2SchemaValidation (6 cases: missing model/api_url,
null-model via default profile, bare-name substitution, non-dict
profile, e2e create_llm_client); full suite 282 passed.
qing
0e9efe4895