[Phase 2.2] Create fact_payments mart

[Flames4fun]

Summary

Create a new fact_payments mart model for Phase 2.2.

Goal

Expose payment-level analytical data in marts, starting from stg_payments, with a clearly documented grain and basic model tests.

Tasks

• Create dbt/models/marts/facts/fact_payments.sql from stg_payments.
• Add order_purchase_date using a safe join by order_id with either:
  • int_orders_enriched, or
  • fact_orders
• Create dbt/models/marts/facts/_fact_payments.yml.
• Add model tests for:
  • not_null
  • relationships
  • grain/uniqueness validation aligned with the final design.

Acceptance Criteria

• dbt build --project-dir ./dbt --profiles-dir ./dbt --select fact_payments passes.
• Grain is documented in YAML and/or model docs.
• Final grain is explicitly defined as: 1 row per payment_key.
• order_purchase_date is populated through a documented join path.
• Tests pass locally.

Out of scope

• No changes to existing marts unless strictly necessary.

Notes

If the chosen join path has tradeoffs, document them briefly in the PR.

[thoalecorn]

Hey bro, I think I have the perfect skills to do this issue, would you be so kind as to assign it to me?

[Flames4fun]

Thanks for taking this one! 🙌

Assigned to you. Please feel free to open a draft PR whenever you start, and if you make any design choice around the join path or model grain, just mention it briefly in the PR description.

Good luck 🚀