feat: ship Tier 1 — auth, authz, rate limits, real notifications, CSV import, billing, backups/DR, privacy

Closes every block in docs/TIER1_PLAN.md from the Claude-scope side. The
homelab / cloud setup steps (SES verification, restore drill, lawyer-
drafted ToS) remain operator-owned but are unblocked.

Block A — Authentication
- Migration 0003: password_hash, email_verified, email_verification_tokens,
  password_reset_tokens, refresh_tokens (with replaced_by family chain).
- Bcrypt hasher, HS256 JWT signer, single-use refresh tokens with rotation
  + replay-detection (revokes the family on reuse).
- /auth/signup, /login, /refresh, /logout, /verify-email,
  /forgot-password, /reset-password — enumeration-safe.
- requireAuth middleware + GET /me.
- Frontend useAuth/useApi with auto-refresh-on-401, login/signup/verify/
  forgot/reset pages, route-guard middleware.

Block B — Authorisation
- EventRepo.GetForHost; Update/Delete scoped by host_id.
- All host routes behind requireAuth + ownership; cross-tenant returns
  404 (no enumeration). ?host_id removed.
- WS auth via short-lived single-use tickets (POST /auth/ws-ticket).
- Tests: TestCrossTenantIsolation — 9 probes.

Block C — Rate limiting
- Redis sliding-window via Lua (atomic ZADD+ZCARD+PEXPIRE).
- Per-route limits matching the plan (signup IP, login IP+email, RSVP/
  access by token, events/guests/tokens by user_id).
- 429 with Retry-After header and JSON body.
- Auth lockout: 5 failed logins → account locked, only password reset
  clears it.
- Frontend: useErrMessage normalises 429 + locked messaging.

Block D — Real notifications
- Migration 0004: provider_message_id, bounce_type, complained columns
  + unsubscribes (CITEXT) suppression table.
- Branded HTML + plaintext templates for verification, reset, invitation,
  confirmation, reminder. Per-page templates avoid html/template's
  contextual-escape collisions.
- Senders: SESv2, Twilio (SMS), SMTP (Mailpit-friendly), Resend HTTP.
- PickEmailSender priority Resend > SMTP > SES > Log — system boots
  cleanly in dev with Mailpit; production flips one env var.
- Webhook endpoints (Twilio status + SES SNS) — bounces add to suppression;
  signature verification stubbed pending creds.
- Auto-send: POST /tokens publishes invitation.send; notifier renders +
  delivers via the configured backend; suppression list honoured.
- Bulk + per-row invitation flow: POST /events/{id}/guests/invitations/bulk
  returns per-guest tokens so phone-only guests can be SMS'd manually.
- Unsubscribe: signed HMAC token (no TTL) + /unsubscribe/[token] page.
- WhatsApp Option A+: wa.me click-to-chat wizard with per-guest progress
  tracking, isLikelyE164 validation, edit-from-wizard.
- Token rotate (POST /tokens/rotate) invalidates the old URL — used by
  the regenerate-link flow.
- Mailpit added to docker-compose for dev inbox.

Block E — CSV import
- Streaming parser: tolerant header detection, UTF-8 BOM + UTF-16 LE/BE
  decoding, row-level validation, 5,000-row cap.
- Strict E.164 phone validation with helpful error message.
- POST /preview + /import + GET /template; preview UI on event page;
  atomic per-batch with dedup on existing emails.

Phone capture across UI
- PhoneInput component: country picker (~50 ISO codes) + national input +
  live E.164 preview + inline length validation.
- Used in Add Guest and Edit Guest modals. Smart paste-handling extracts
  country code from full E.164 strings.

Block F — Billing (Stripe)
- Migration 0005: subscriptions table (user_id → tier/status/period_end +
  Stripe customer/sub ids). Partial unique index keeps one granting sub
  per user.
- internal/billing: Tier + Limits model (Free 1/50, Pro 10/1000, Business
  ∞/5000), Stripe SDK wrapper with IgnoreAPIVersionMismatch for newer
  account API versions.
- /billing/checkout-session, /billing/portal, /billing/status,
  /webhooks/stripe (signature-verified, lifecycle events).
- Tier enforcement: 402 on POST /events, /guests, /import with
  {error, reason, tier, used, limit, upgrade_url} body.
- Frontend: useBilling composable, /dashboard/billing page (current plan,
  usage bars, tier cards), global UpgradeModal triggered by useApi's
  402 interceptor.
- Customer portal kept for self-service cancel/payment-method changes.

Block G — Backups & DR (application side)
- Every migration has a tested .down.sql.
- TestMigrationRoundtrip applies all ups → all downs → all ups against a
  fresh container; catches asymmetric down migrations.
- cmd/restore-verify: 28-check post-restore invariant tool (schema
  presence, no orphans across 10 FK relationships, email uniqueness,
  single-active subscription, row-count snapshot).
- docs/RUNBOOK_RESTORE.md: 9-step restore procedure with RTO/RPO
  targets, drill instructions, rollback path.

Block H — Privacy compliance (application side)
- Migration 0006: deleted_at + terms_accepted_at + privacy_policy_accepted_at
  on users. Partial index on email for live-only uniqueness.
- GET /me/data-export — synchronous JSON dump (user, events, guests,
  tokens, rsvps, access_logs, notifications).
- DELETE /me — soft-delete with PII scrub + refresh-token revocation;
  re-signup with same email works.
- POST /me/accept-terms — idempotent consent recording.
- Frontend /privacy + /terms placeholder pages with substantive (pending
  legal review) copy; footer links; signup terms checkbox; TermsGateModal
  for accounts created before the rollout; export + delete buttons on
  /dashboard/billing.

Tests
- All migrations verified up/down/up.
- Integration suite: TestE2EHappyPath, TestAuthFlow, TestCrossTenantIsolation,
  TestRateLimitSignup, TestLoginLockout, TestUnsubscribeFlow,
  TestSESBounceWebhook, TestTwilioStatusWebhook, TestCsvImportFlow,
  TestCsvImportAtomicRollback, TestBulkIssueInvitations, TestBulkIssueExplicitSubset,
  TestTokenIssuePublishesInvitation, TestTokenIssueWithoutGuestEmailSkipsInvitation,
  TestGuestUpdate, TestGuestDelete, TestTokenRotate, TestSMTPSenderAgainstMailpit,
  TestFreeTierEventLimit, TestFreeTierGuestLimit, TestBusinessTierBypassesLimits,
  TestDataExport, TestDeleteMe, TestAcceptTerms, TestMigrationRoundtrip.
  Full suite runs in ~120s against real Postgres + NATS + Redis + Mailpit.
- Unit suite green across internal/auth, internal/csvimport,
  internal/notification, internal/ratelimit, internal/domain.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/notification/resend_sender.go

@@ -0,0 +1,134 @@
+package notification
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+// ResendConfig configures the Resend HTTP sender. APIKey is required;
+// FromEmail is the sending address on a domain you've verified in the
+// Resend dashboard.
+type ResendConfig struct {
+	APIKey    string
+	FromEmail string
+	FromName  string
+
+	// HTTPClient overrides the default client (mostly so tests can point
+	// at httptest.Server). Leave nil for production.
+	HTTPClient *http.Client
+	BaseURL    string // overrideable for tests; defaults to https://api.resend.com
+}
+
+// ResendEmailSender posts emails through https://api.resend.com/emails.
+// Implements auth.EmailSender + GuestEmailDispatcher.
+type ResendEmailSender struct {
+	cfg    ResendConfig
+	tpls   *Templates
+	from   string
+	client *http.Client
+	url    string
+}
+
+func NewResendEmailSender(cfg ResendConfig, tpls *Templates) (*ResendEmailSender, error) {
+	if cfg.APIKey == "" {
+		return nil, errors.New("resend: APIKey required")
+	}
+	if cfg.FromEmail == "" {
+		return nil, errors.New("resend: FromEmail required")
+	}
+	from := cfg.FromEmail
+	if cfg.FromName != "" {
+		from = fmt.Sprintf("%s <%s>", cfg.FromName, cfg.FromEmail)
+	}
+	cli := cfg.HTTPClient
+	if cli == nil {
+		cli = &http.Client{Timeout: 15 * time.Second}
+	}
+	base := cfg.BaseURL
+	if base == "" {
+		base = "https://api.resend.com"
+	}
+	return &ResendEmailSender{cfg: cfg, tpls: tpls, from: from, client: cli, url: base + "/emails"}, nil
+}
+
+// --- auth.EmailSender ---
+
+func (s *ResendEmailSender) SendVerification(ctx context.Context, to, name, link string) error {
+	_, err := s.sendTemplated(ctx, to, "Verify your GuestGuard email",
+		TmplVerification, map[string]any{"Name": name, "Link": link})
+	return err
+}
+
+func (s *ResendEmailSender) SendPasswordReset(ctx context.Context, to, name, link string) error {
+	_, err := s.sendTemplated(ctx, to, "Reset your GuestGuard password",
+		TmplPasswordReset, map[string]any{"Name": name, "Link": link, "ExpiryHumane": "1 hour"})
+	return err
+}
+
+// --- GuestEmailDispatcher ---
+
+func (s *ResendEmailSender) SendGuest(ctx context.Context, to, subject string, name TemplateName, data map[string]any) (string, error) {
+	return s.sendTemplated(ctx, to, subject, name, data)
+}
+
+// --- internals ---
+
+type resendRequest struct {
+	From    string   `json:"from"`
+	To      []string `json:"to"`
+	Subject string   `json:"subject"`
+	HTML    string   `json:"html"`
+	Text    string   `json:"text"`
+}
+
+type resendResponse struct {
+	ID      string `json:"id"`
+	Message string `json:"message,omitempty"`
+}
+
+func (s *ResendEmailSender) sendTemplated(ctx context.Context, to, subject string, name TemplateName, data map[string]any) (string, error) {
+	if data == nil {
+		data = map[string]any{}
+	}
+	data["Subject"] = subject
+	html, text, err := s.tpls.Render(name, data)
+	if err != nil {
+		return "", err
+	}
+
+	body, _ := json.Marshal(resendRequest{
+		From:    s.from,
+		To:      []string{to},
+		Subject: subject,
+		HTML:    html,
+		Text:    text,
+	})
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.url, bytes.NewReader(body))
+	if err != nil {
+		return "", err
+	}
+	req.Header.Set("Authorization", "Bearer "+s.cfg.APIKey)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := s.client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("resend: do: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
+	if resp.StatusCode >= 300 {
+		return "", fmt.Errorf("resend: status %d: %s", resp.StatusCode, string(respBody))
+	}
+	var parsed resendResponse
+	if err := json.Unmarshal(respBody, &parsed); err != nil {
+		return "", fmt.Errorf("resend: parse: %w", err)
+	}
+	return parsed.ID, nil
+}