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/core/config.py

@@ -0,0 +1,17 @@
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8")
+
+    secret_key: str = "change_me_in_production"
+    sqlite_path: str = "./data/homelab.db"
+    config_path: str = "./config.yml"
+    cors_origins: list[str] = ["http://localhost:5173", "http://localhost:3000"]
+
+    # JWT
+    algorithm: str = "HS256"
+    access_token_expire_minutes: int = 1440  # 24h
+
+
+settings = Settings()

backend/app/core/security.py

@@ -0,0 +1,30 @@
+from datetime import datetime, timedelta, timezone
+
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+
+from app.core.config import settings
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+
+def verify_password(plain: str, hashed: str) -> bool:
+    return pwd_context.verify(plain, hashed)
+
+
+def hash_password(password: str) -> str:
+    return pwd_context.hash(password)
+
+
+def create_access_token(subject: str) -> str:
+    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.access_token_expire_minutes)
+    payload = {"sub": subject, "exp": expire}
+    return jwt.encode(payload, settings.secret_key, algorithm=settings.algorithm)
+
+
+def decode_token(token: str) -> str | None:
+    try:
+        payload = jwt.decode(token, settings.secret_key, algorithms=[settings.algorithm])
+        return payload.get("sub")
+    except JWTError:
+        return None