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>

Makefile

@@ -0,0 +1,55 @@
+.PHONY: build run test integration-test vet tidy fmt up down logs clean fraud-test fraud-install proto
+
+build:
+	go build -o bin/api ./cmd/api
+
+run:
+	go run ./cmd/api
+
+test:
+	go test ./... -race -count=1
+
+# Integration tests spin up real Postgres + NATS via testcontainers and an
+# in-process gRPC stub for the fraud engine. Requires Docker.
+integration-test:
+	go test -tags=integration -count=1 -timeout=5m ./test/integration/...
+
+vet:
+	go vet ./...
+
+tidy:
+	go mod tidy
+
+fmt:
+	gofmt -s -w .
+
+up:
+	docker compose up --build -d
+
+down:
+	docker compose down
+
+logs:
+	docker compose logs -f api fraud-engine nats
+
+fraud-install:
+	cd fraud-engine && python3 -m venv .venv && . .venv/bin/activate && pip install -e ".[dev]"
+
+fraud-test:
+	cd fraud-engine && . .venv/bin/activate && python -m pytest -v
+
+# Regenerates Go + Python stubs from proto/fraud/v1/fraud.proto.
+# Requires fraud-engine venv (provides bundled protoc via grpcio-tools)
+# and the Go plugins (protoc-gen-go, protoc-gen-go-grpc) on $(go env GOPATH)/bin.
+proto:
+	@command -v protoc-gen-go >/dev/null || go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.34.2
+	@command -v protoc-gen-go-grpc >/dev/null || go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.5.1
+	cd fraud-engine && . .venv/bin/activate && \
+	  PATH="$$(go env GOPATH)/bin:$$PATH" python -m grpc_tools.protoc -I ../proto \
+	    --go_out=.. --go_opt=module=github.com/alchemistkay/guestguard \
+	    --go-grpc_out=.. --go-grpc_opt=module=github.com/alchemistkay/guestguard \
+	    --python_out=. --pyi_out=. --grpc_python_out=. \
+	    ../proto/fraud/v1/fraud.proto
+
+clean:
+	rm -rf bin fraud-engine/.venv