feat: authentication — register, login, JWT, tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/deps.py

@@ -0,0 +1,28 @@
+from fastapi import Depends, HTTPException, status
+from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.database import get_db
+from app.models.user import User
+from app.services.auth import decode_access_token
+
+security = HTTPBearer()
+
+
+async def get_current_user(
+    credentials: HTTPAuthorizationCredentials = Depends(security),
+    db: AsyncSession = Depends(get_db),
+) -> User:
+    user_id = decode_access_token(credentials.credentials)
+    if user_id is None:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token"
+        )
+    result = await db.execute(select(User).where(User.id == user_id))
+    user = result.scalar_one_or_none()
+    if user is None or not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found"
+        )
+    return user