Migration tracking issue for CTModels breaking change.

Context

This migration manages the transition from CTModels v0.6.10-beta to v0.7.0-beta.
Note: A v0.7.0 release already exists and will be merged into this branch once the breaking change migration is complete.

Affected Packages

• CTDirect v0.17.5-beta (depends on CTModels)
• CTFlows v0.8.10-beta (depends on CTModels)
• OptimalControl v1.1.8-beta (depends on CTModels)

Strategy

1. Create v0.7.0-beta from this branch
2. Test breakages with dependent packages
3. Adapt breaking packages if needed
4. Merge final v0.7.0 once migration is complete