Epic: #2072

File: src/ol_dbt/models/marts/combined/marts__combined_course_enrollment_detail.sql

Problem: Directly references 14 intermediate models across bootcamps, combined, micromasters, mitxonline, and mitxpro instead of using dimensional layer models.

Target state: Rewrite to use tfact_enrollment, dim_course_run, dim_user, and dim_program from the dimensional layer.