feat: build core API, fraud engine, notifier, and frontend

Phase 1 — Core API (Go):
- Events, guests, tokens, RSVPs CRUD on PostgreSQL via pgx/v5
- HMAC-signed per-guest tokens with format validation
- Health endpoint with DB ping, slog JSON logging, graceful shutdown

Phase 2 — NATS + Fraud Engine:
- NATS JetStream pub/sub with explicit-ack consumers
- Python/FastAPI fraud engine with heuristic risk scoring
  (fingerprint mismatch, IP change, missing signals, repeated access)
- gRPC sync scoring with 250ms fail-open timeout
- Per-guest baseline tracking; risk bands low/medium/high/block

Phase 3 — Notifications + Frontend:
- Notification worker scaffolding (Twilio/SES stubs, retry/backoff)
- Nuxt 3 frontend with Tailwind dark theme + brand green
- Live monitor via WebSocket with auto-reconnect
- Activity history endpoint backfills monitor with RSVPs +
  scored access checks (including blocked attempts)

UX polish:
- Marketing-friendly landing page (hero mockup, how-it-works,
  features, use cases, testimonials, FAQ, final CTA)
- Animated layered card mockups on landing + new-event page
- Plus-ones stepper, RSVP status badges, filter buttons
- Friendly access-check labels (Verified/Review/Suspicious/Blocked)
- Dashboard hydration fix via ClientOnly wrapper

Infrastructure:
- docker-compose for full local dev (postgres, nats, api,
  fraud-engine, notifier, frontend)
- Multi-stage Dockerfiles, non-root UID 1000
- Integration tests with testcontainers-go

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

internal/storage/rsvps.go

@@ -0,0 +1,135 @@
+package storage
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/alchemistkay/guestguard/internal/domain"
+)
+
+type RSVPRepo struct {
+	pool *pgxpool.Pool
+}
+
+func NewRSVPRepo(db *DB) *RSVPRepo {
+	return &RSVPRepo{pool: db.Pool}
+}
+
+type CreateRSVPParams struct {
+	GuestID           uuid.UUID
+	Response          domain.RSVPResponse
+	PlusOnes          int
+	DietaryNotes      *string
+	DeviceFingerprint map[string]any
+	IPAddress         string
+	RiskScore         *int
+}
+
+func (r *RSVPRepo) Create(ctx context.Context, p CreateRSVPParams) (*domain.RSVP, error) {
+	var fpJSON []byte
+	if p.DeviceFingerprint != nil {
+		b, err := json.Marshal(p.DeviceFingerprint)
+		if err != nil {
+			return nil, fmt.Errorf("marshal fingerprint: %w", err)
+		}
+		fpJSON = b
+	}
+
+	var ip *string
+	if p.IPAddress != "" {
+		ip = &p.IPAddress
+	}
+
+	const q = `
+        INSERT INTO rsvps (guest_id, response, plus_ones, dietary_notes,
+                           device_fingerprint, ip_address, risk_score)
+        VALUES ($1, $2, $3, $4, $5, $6::inet, $7)
+        RETURNING id, guest_id, response, plus_ones, dietary_notes,
+                  submitted_at, device_fingerprint, ip_address::text, risk_score
+    `
+
+	row := r.pool.QueryRow(ctx, q,
+		p.GuestID, p.Response, p.PlusOnes, p.DietaryNotes,
+		fpJSON, ip, p.RiskScore,
+	)
+
+	rs, err := scanRSVP(row)
+	if err != nil {
+		var pgErr *pgconn.PgError
+		if errors.As(err, &pgErr) && pgErr.Code == "23505" {
+			return nil, domain.ErrRSVPAlreadySubmitted
+		}
+		return nil, err
+	}
+	return rs, nil
+}
+
+// RSVPActivity is a denormalised RSVP entry for the activity feed —
+// includes the guest's name so the API can hand it to the frontend
+// without a separate lookup.
+type RSVPActivity struct {
+	GuestID     uuid.UUID
+	GuestName   string
+	Response    string
+	PlusOnes    int
+	SubmittedAt time.Time
+}
+
+// ListRecentByEvent returns the most recent RSVPs for an event, newest first.
+func (r *RSVPRepo) ListRecentByEvent(ctx context.Context, eventID uuid.UUID, limit int) ([]RSVPActivity, error) {
+	if limit <= 0 || limit > 200 {
+		limit = 50
+	}
+	const q = `
+        SELECT r.guest_id, g.name, r.response, r.plus_ones, r.submitted_at
+        FROM rsvps r
+        JOIN guests g ON g.id = r.guest_id
+        WHERE g.event_id = $1
+        ORDER BY r.submitted_at DESC
+        LIMIT $2
+    `
+	rows, err := r.pool.Query(ctx, q, eventID, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var out []RSVPActivity
+	for rows.Next() {
+		var a RSVPActivity
+		if err := rows.Scan(&a.GuestID, &a.GuestName, &a.Response, &a.PlusOnes, &a.SubmittedAt); err != nil {
+			return nil, err
+		}
+		out = append(out, a)
+	}
+	return out, rows.Err()
+}
+
+func scanRSVP(s rowScanner) (*domain.RSVP, error) {
+	var (
+		rs     domain.RSVP
+		fpJSON []byte
+		ip     *string
+	)
+	err := s.Scan(
+		&rs.ID, &rs.GuestID, &rs.Response, &rs.PlusOnes, &rs.DietaryNotes,
+		&rs.SubmittedAt, &fpJSON, &ip, &rs.RiskScore,
+	)
+	if err != nil {
+		return nil, err
+	}
+	if len(fpJSON) > 0 {
+		_ = json.Unmarshal(fpJSON, &rs.DeviceFingerprint)
+	}
+	if ip != nil {
+		rs.IPAddress = ip
+	}
+	return &rs, nil
+}