Refactors modeling criteria for SaaS metrics and dbt funnel

Updates project specifications to focus on SaaS health metrics and growth funnel analysis using SQL and dbt, improving clarity for stakeholders and aligning outputs with dashboard integration.

Replaces previous financial consulting examples with SaaS-specific logic, adds cohort and retention analysis, and details expected deliverables, data models, and integration points for enhanced business insight and technical reproducibility.

Author: raphaela-nawa