REMOVED all hardcoded default backend/model values from defaultModelsConfig.
Now ~/.codeagent/models.json is REQUIRED - missing config returns clear error
with example configuration.
BREAKING CHANGE: Users must configure ~/.codeagent/models.json before using
--agent or parallel tasks with agent: field.
Generated with SWE-Agent.ai
Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>