fix: 7 Bugs behoben – Backend+Frontend lauffähig getestet

Backend-Fixes:
- vehicles-Relation in Account-Model ergänzt (500er bei Auth)
- security.py: bcrypt direkt statt passlib (bcrypt 5.x-Kompatibilität)
- auth.py Login: selectinload(User.role) gegen Lazy-Loading-500er
- equipment_group.py: LocationRef-Import via TYPE_CHECKING

Frontend-Fixes:
- api.ts: Python-Docstring durch JS-Kommentar ersetzt
- AppLayout.tsx: AddressBook→Contact (existiert nicht in lucide-react)
- package.json: axios-Dependency ergänzt

Tests bestanden:
- Health 200, Register 201, Login 200, Projects CRUD 200, alle API-Listen 200
- tsc --noEmit: sauber, vite build: erfolgreich

backend/app/api/v1/auth.py

@@ -3,6 +3,7 @@
 from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import selectinload
 
 from app.api.deps import get_current_user
 from app.core.security import (
@@ -116,7 +117,9 @@ async def login(
     session: AsyncSession = Depends(get_async_session),
 ):
     """Authenticate user with email and password."""
-    result = await session.execute(select(User).where(User.email == body.email))
+    result = await session.execute(
+        select(User).options(selectinload(User.role)).where(User.email == body.email)
+    )
     user = result.scalars().first()
 
     if not user or not verify_password(body.password, user.password_hash):