Update the Domain Models section of docs/specification.md to reflect the
introduction of DomainBaseModel (domain/models/base.py) as the shared Pydantic
base class for domain entities with the canonical model_config.
Changes:
- docs/specification.md: Update Domain Models subsection to mention
DomainBaseModel and the canonical config (str_strip_whitespace,
validate_assignment, arbitrary_types_allowed=False, populate_by_name,
use_enum_values). Clarify that classes with different config requirements
may still subclass BaseModel directly.
Triggered by PR #2014 (refactor(domain): extract shared model_config into
a base Pydantic model, closes#1941).
Approved via proposal issue #2440.
ISSUES CLOSED: #2440
freemo