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>

docker-compose.yml

@@ -0,0 +1,106 @@
+services:
+  postgres:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: guestguard
+      POSTGRES_PASSWORD: guestguard
+      POSTGRES_DB: guestguard
+    ports:
+      - "5432:5432"
+    volumes:
+      - postgres-data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U guestguard -d guestguard"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+  nats:
+    image: nats:2.10-alpine
+    command:
+      - "-js"
+      - "-sd"
+      - "/data"
+      - "-m"
+      - "8222"
+    ports:
+      - "4222:4222"
+      - "8222:8222"
+    volumes:
+      - nats-data:/data
+    healthcheck:
+      test: ["CMD", "wget", "-qO-", "http://localhost:8222/healthz"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+  api:
+    build:
+      context: .
+      dockerfile: cmd/api/Dockerfile
+    environment:
+      GG_ENV: development
+      GG_HTTP_ADDR: :8080
+      GG_DATABASE_URL: postgres://guestguard:guestguard@postgres:5432/guestguard?sslmode=disable
+      GG_NATS_URL: nats://nats:4222
+      GG_FRAUD_GRPC_ADDR: fraud-engine:9091
+      GG_FRAUD_GRPC_TIMEOUT: 250ms
+      GG_TOKEN_SECRET: dev-only-insecure-secret-change-me
+    ports:
+      - "8080:8080"
+    depends_on:
+      postgres:
+        condition: service_healthy
+      nats:
+        condition: service_healthy
+    restart: unless-stopped
+
+  fraud-engine:
+    build:
+      context: ./fraud-engine
+      dockerfile: Dockerfile
+    environment:
+      GG_ENV: development
+      GG_HTTP_ADDR: 0.0.0.0:8081
+      GG_GRPC_ADDR: 0.0.0.0:9091
+      GG_NATS_URL: nats://nats:4222
+    ports:
+      - "8081:8081"
+      - "9091:9091"
+    depends_on:
+      nats:
+        condition: service_healthy
+    restart: unless-stopped
+
+  notifier:
+    build:
+      context: .
+      dockerfile: cmd/notifier/Dockerfile
+    environment:
+      GG_ENV: development
+      GG_DATABASE_URL: postgres://guestguard:guestguard@postgres:5432/guestguard?sslmode=disable
+      GG_NATS_URL: nats://nats:4222
+    depends_on:
+      postgres:
+        condition: service_healthy
+      nats:
+        condition: service_healthy
+    restart: unless-stopped
+
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: Dockerfile
+    environment:
+      NODE_ENV: production
+      NUXT_PUBLIC_API_BASE: http://localhost:8080
+      NUXT_PUBLIC_WS_BASE: ws://localhost:8080
+    ports:
+      - "3000:3000"
+    depends_on:
+      - api
+    restart: unless-stopped
+
+volumes:
+  postgres-data:
+  nats-data: