[backend] Add data models and migrations

Repo: · Issue: #979 Status: Open · Priority: P2 Assignee: Unassigned

Description

Summary

Create NBA persistence models and migrations for signals, rules, recommendations, and executions.

Scope

• Add tables/models for NbaSignal, NbaRule, NbaAction, NbaRecommendation, NbaExecution
• Include merchant/status/source/confidence/urgency/impact/lifecycle metadata

Role

Backend/DB

Estimate

2–3 days

Implementation Notes

Dash adds notes here while working

Related

Link to people, meetings, dependent tickets