Version-control Supabase schema: add migrations workflow (Supabase CLI)

[syed-reza98]

Why

Docs flag schema not version-controlled as a critical production risk (DB drift, no audit trail).

Goal

Introduce a migration workflow so schema changes are captured in-repo and reproducible.

Tasks

• Add supabase/ directory (or migrations/) with pulled schema migrations
• Document commands in README:
  • supabase migration pull
  • supabase db reset (local)
  • supabase db push
• Add CI check that ensures migrations apply cleanly (optional: local DB in CI)
• Add guidance for applying changes safely (breaking changes notes)

Acceptance criteria

• A fresh clone can reproduce DB schema from migrations
• Schema drift is detectable (PR diff shows SQL)

References

• docs/01_CODEBASE_ARCHITECTURE_REVIEW.md: Schema not version-controlled (critical)
• docs/02_FEATURES_REQUIREMENTS_BEST_PRACTICES.md: Issue 4 DB schema migrations

[syed-reza98]

Closed as completed via PR #71.