chore: initial project setup with backend, frontend, CI/CD, and documentation

Add complete NexaFabric project structure including:
- FastAPI backend with SQLAlchemy models, JWT auth, RBAC, audit logging, and provider interfaces
- React + TypeScript frontend with Vite, Tailwind CSS, TanStack Query, and Zustand
- Docker Compose configuration for PostgreSQL, Redis, API, worker, frontend, and nginx
- GitHub Actions and GitLab CI workflows for testing, linting, building, and security scanning
- Environment

docker-compose.yml

@@ -0,0 +1,69 @@
+services:
+  postgres:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_DB: nexafabric
+      POSTGRES_USER: nexafabric
+      POSTGRES_PASSWORD: nexafabric
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U nexafabric -d nexafabric"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+    volumes:
+      - postgres-data:/var/lib/postgresql/data
+
+  redis:
+    image: redis:7-alpine
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+
+  api:
+    build:
+      context: ./backend
+    env_file: .env
+    depends_on:
+      postgres:
+        condition: service_healthy
+      redis:
+        condition: service_healthy
+    healthcheck:
+      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:8000/healthz')"]
+      interval: 15s
+      timeout: 5s
+      retries: 5
+
+  worker:
+    build:
+      context: ./backend
+    env_file: .env
+    command: ["python", "-m", "app.workers.worker"]
+    depends_on:
+      api:
+        condition: service_healthy
+
+  frontend:
+    build:
+      context: ./frontend
+    environment:
+      VITE_API_BASE_URL: /api/v1
+    depends_on:
+      api:
+        condition: service_healthy
+
+  proxy:
+    image: nginx:1.27-alpine
+    ports:
+      - "8080:80"
+    volumes:
+      - ./nginx/default.conf:/etc/nginx/conf.d/default.conf:ro
+    depends_on:
+      - api
+      - frontend
+
+volumes:
+  postgres-data:
+