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/postgres.go

@@ -0,0 +1,115 @@
+package storage
+
+import (
+	"context"
+	"embed"
+	"fmt"
+	"io/fs"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+//go:embed migrations/*.sql
+var migrationsFS embed.FS
+
+type DB struct {
+	Pool *pgxpool.Pool
+}
+
+func NewDB(ctx context.Context, dsn string) (*DB, error) {
+	cfg, err := pgxpool.ParseConfig(dsn)
+	if err != nil {
+		return nil, fmt.Errorf("parse dsn: %w", err)
+	}
+	cfg.MaxConnLifetime = 30 * time.Minute
+	cfg.MaxConns = 10
+
+	pool, err := pgxpool.NewWithConfig(ctx, cfg)
+	if err != nil {
+		return nil, fmt.Errorf("connect pool: %w", err)
+	}
+
+	pingCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+	if err := pool.Ping(pingCtx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("ping db: %w", err)
+	}
+
+	return &DB{Pool: pool}, nil
+}
+
+func (db *DB) Close() {
+	db.Pool.Close()
+}
+
+func (db *DB) Migrate(ctx context.Context) error {
+	_, err := db.Pool.Exec(ctx, `
+        CREATE TABLE IF NOT EXISTS schema_migrations (
+            version VARCHAR(255) PRIMARY KEY,
+            applied_at TIMESTAMPTZ NOT NULL DEFAULT now()
+        )
+    `)
+	if err != nil {
+		return fmt.Errorf("create migrations table: %w", err)
+	}
+
+	entries, err := fs.ReadDir(migrationsFS, "migrations")
+	if err != nil {
+		return fmt.Errorf("read migrations: %w", err)
+	}
+
+	type migration struct {
+		version string
+		path    string
+	}
+	var ups []migration
+	for _, e := range entries {
+		name := e.Name()
+		if !strings.HasSuffix(name, ".up.sql") {
+			continue
+		}
+		version := strings.TrimSuffix(name, ".up.sql")
+		ups = append(ups, migration{version: version, path: "migrations/" + name})
+	}
+	sort.Slice(ups, func(i, j int) bool { return ups[i].version < ups[j].version })
+
+	for _, m := range ups {
+		var exists bool
+		err := db.Pool.QueryRow(ctx,
+			"SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version=$1)",
+			m.version,
+		).Scan(&exists)
+		if err != nil {
+			return fmt.Errorf("check migration %s: %w", m.version, err)
+		}
+		if exists {
+			continue
+		}
+
+		sqlBytes, err := migrationsFS.ReadFile(m.path)
+		if err != nil {
+			return fmt.Errorf("read %s: %w", m.path, err)
+		}
+		tx, err := db.Pool.Begin(ctx)
+		if err != nil {
+			return fmt.Errorf("begin tx for %s: %w", m.version, err)
+		}
+		if _, err := tx.Exec(ctx, string(sqlBytes)); err != nil {
+			_ = tx.Rollback(ctx)
+			return fmt.Errorf("apply %s: %w", m.version, err)
+		}
+		if _, err := tx.Exec(ctx, "INSERT INTO schema_migrations(version) VALUES($1)", m.version); err != nil {
+			_ = tx.Rollback(ctx)
+			return fmt.Errorf("record %s: %w", m.version, err)
+		}
+		if err := tx.Commit(ctx); err != nil {
+			return fmt.Errorf("commit %s: %w", m.version, err)
+		}
+	}
+
+	return nil
+}