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/app/schemas/canvas.py

@@ -0,0 +1,21 @@
+from pydantic import BaseModel
+
+from app.schemas.edges import EdgeResponse
+from app.schemas.nodes import NodeResponse
+
+
+class NodePosition(BaseModel):
+    id: str
+    x: float
+    y: float
+
+
+class CanvasSaveRequest(BaseModel):
+    node_positions: list[NodePosition] = []
+    viewport: dict = {}
+
+
+class CanvasStateResponse(BaseModel):
+    nodes: list[NodeResponse]
+    edges: list[EdgeResponse]
+    viewport: dict