📝 docs(adr): ADR-0028/0029/0030 — passwordless auth + Mailpit + BDD email strategy

Three coordinated ADRs Proposed for the auth-completion sprint, requested
by user: signup → magic link by email → OpenID Connect Authorization
Code with PKCE, all integrated with Mailpit (already locally available
as docker image) and BDD parallel testing strategy.

ADR-0028 — Passwordless auth migration (sequenced):
- Phase A: magic link by email (no password storage, JWT issued on consume)
- Phase B: OpenID Connect Code flow with PKCE (cross-product SSO, mkcert
  for local HTTPS callbacks)
- Phase C (separate ADR later): decommission password auth

ADR-0029 — Email infra:
- Mailpit (axllent/mailpit:latest) for local dev + BDD (image already
  pulled, 51 MB), defaults SMTP :1025 / HTTP API :8025
- pkg/email.Sender interface for provider portability
- Production sender choice DEFERRED (separate ADR when volume / SLA
  / compliance requirements known — likely AWS SES or Postmark)

ADR-0030 — BDD email parallel strategy:
- Per-test recipient scoping: each scenario generates a unique address
  <scenario-key>-<8hex>@bdd.local
- Mailpit HTTP API filters by recipient → no cross-scenario interference
- pkg/bdd/mailpit/ helper package + pkg/bdd/steps/email_steps.go
- Preserves the 2.85x parallel BDD speedup from PR #35

Implementation lands in subsequent PRs ; today only the design is shipped.
README index updated with 3 new entries (0028/0029/0030 all Proposed).

adr/README.md

@@ -31,6 +31,9 @@ This directory contains the Architecture Decision Records (ADRs) for the dance-l
 | [0025](0025-bdd-scenario-isolation-strategies.md) | BDD Scenario Isolation Strategies | Implemented |
 | [0026](0026-composite-info-endpoint.md) | Composite Info Endpoint vs Separate Calls | Implemented |
 | [0027](0027-ollama-tier1-onboarding.md) | Ollama Tier 1 onboarding via meta-trainer-bootstrap | Proposed |
+| [0028](0028-passwordless-auth-migration.md) | Passwordless authentication: magic link → OpenID Connect | Proposed |
+| [0029](0029-email-infrastructure-mailpit.md) | Email infrastructure: Mailpit local + production deferred | Proposed |
+| [0030](0030-bdd-email-parallel-strategy.md) | BDD email assertions with parallel test execution | Proposed |
 
 > **Note** : numbers `0011` and `0014` are not currently in use. Reserved for future ADRs or representing previously deleted entries.