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

scripts/backup.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env sh
+set -eu
+
+mkdir -p backups
+docker compose exec -T postgres pg_dump -U nexafabric nexafabric >"backups/nexafabric-$(date +%Y%m%d-%H%M%S).sql"
+

scripts/install-agent.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env sh
+set -eu
+
+install -d /usr/local/lib/nexafabric /usr/local/bin /etc/nexafabric
+install -m 0755 agent/nexafabric_agent.py /usr/local/lib/nexafabric/nexafabric_agent.py
+cat >/usr/local/bin/nexafabric-agent <<'EOF'
+#!/usr/bin/env sh
+exec python3 /usr/local/lib/nexafabric/nexafabric_agent.py
+EOF
+chmod 0755 /usr/local/bin/nexafabric-agent
+install -m 0644 deploy/systemd/nexafabric-agent.service /etc/systemd/system/nexafabric-agent.service
+systemctl daemon-reload
+systemctl enable --now nexafabric-agent.service
+

scripts/restore.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env sh
+set -eu
+
+if [ $# -ne 1 ]; then
+  echo "Usage: scripts/restore.sh backups/file.sql" >&2
+  exit 1
+fi
+
+docker compose exec -T postgres psql -U nexafabric nexafabric <"$1"
+