feat: Phase 1 scaffold — frontend canvas + backend skeleton

Frontend:
- Vite + React 18 + TypeScript + Tailwind v4 + Shadcn/ui
- React Flow v12 canvas with all 11 node types and 5 edge types
- Dark theme with project design system (cyan, green, orange, purple accents)
- Collapsible sidebar, toolbar, detail panel
- Zustand store for canvas state
- Demo data with 10 nodes and 10 edges

Backend:
- FastAPI + SQLAlchemy async + SQLite (Python 3.13)
- DB models: Node, Edge, CanvasState, PendingDevice, ScanRun
- REST API routes: auth, nodes, edges, canvas, scan, status (WebSocket)
- JWT auth + bcrypt via config.yml
- Pydantic v2 schemas

Infra:
- GitHub Actions quality + security workflows
- .gitignore, .env.example, verify-tooling.sh, security-check.sh

backend/requirements.txt

@@ -0,0 +1,23 @@
+# Requires Python 3.13+ (3.14 not yet supported by pydantic-core)
+fastapi==0.115.0
+uvicorn[standard]==0.30.6
+sqlalchemy[asyncio]==2.0.35
+aiosqlite==0.20.0
+alembic==1.13.3
+pydantic==2.9.2
+pydantic-settings==2.5.2
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+python-multipart==0.0.12
+apscheduler==3.10.4
+python-nmap==0.7.1
+pyyaml==6.0.2
+websockets==13.1
+httpx==0.27.2
+
+# Dev
+ruff==0.6.9
+mypy==1.11.2
+pytest==8.3.3
+pytest-asyncio==0.24.0
+pytest-cov==5.0.0