ADR-0001/6: open implementing PR feat/0001-global-email-uniqueness → dev

[TheBoomerDev]

Summary

Open the implementing PR feat/0001-global-email-uniqueness on cargoffer/education_backend,
targeting dev. Body cites this ADR chain, includes the audit-1 finding,
the 6-step checklist with linked issues A–E, and the reviewer-validation checklist.

Spec

The decision lives at https://github.com/cargoffer/education_backend/blob/feat/adr-0001-global-email-uniqueness/docs/adr/0001-global-email-uniqueness.md. Maps to § Implementation Plan → 6. Branch + PR.

Acceptance criteria

• Branch feat/0001-global-email-uniqueness off dev (per backend/AGENTS.md convention).
• PR body links all of:
  • ADR (this repo, branch tip)
  • Issue A (audit) — confirm 0 duplicate emails found
  • Issue B (migration 002) — apply up() & test
  • Issue C (schema cleanup) — User.ts unique:true removed
  • Issue D (tests) — auth-contract + migration precision tests green
  • Issue E (docs) — AGENTS.md and docs/test-audit.md updated
• All 6 PR-derived Validation Criteria checkboxes from §Validation Criteria are checked.
• gh pr create opens into #N. URL added to portal PR https://github.com/cargoffer/education_portal/pull/81 final checklist.

Out of scope

• Frontend integration tests.

Dependencies

• BLOCKED BY issues A–E all closed.

References

• ADR: https://github.com/cargoffer/education_backend/blob/feat/adr-0001-global-email-uniqueness/docs/adr/0001-global-email-uniqueness.md
• backend/AGENTS.md branch conventions