cog

cbe2b4fa - fix: address review round 2 — nullable bug, dead fields, error handling

fix: address review round 2 — nullable bug, dead fields, error handling - Fix nullable incorrectly set on non-required fields instead of field.Type.Nullable (debug: bool = False was appearing nullable) - Remove dead CogArrayType/CogArrayDisplay struct fields (hardcoded in coreSchema, never read from struct) - Distinguish os.ErrNotExist from permission errors in cross-file resolution; warn on parse failures instead of silently ignoring - Fix bare dict/list JSON Schema examples in architecture docs - Add regression tests: defaulted non-Optional field not nullable, Optional field nullable in JSON Schema, dict[str, Tensor] errors instead of silently producing SchemaAny (both top-level and inside BaseModel fields)