fix: resolve indentation and import errors in backend

- Fix indentation in main.py (scheduler if/else blocks)
- Fix indentation in deps.py (credentials check)
- Fix indentation in auctions.py (filter blocks)
- Add BackgroundTasks import to admin.py
- Fix settings import in yield_domains.py (use get_settings())

backend/app/api/admin.py

@@ -11,7 +11,7 @@ Provides admin-only access to:
 from datetime import datetime, timedelta
 from pathlib import Path
 from typing import Optional
-from fastapi import APIRouter, HTTPException, status, Depends
+from fastapi import APIRouter, HTTPException, status, Depends, BackgroundTasks
 from pydantic import BaseModel, EmailStr
 from sqlalchemy import select, func, desc
 

backend/app/api/yield_domains.py

@@ -15,7 +15,9 @@ from sqlalchemy.orm import Session
 from app.api.deps import get_db, get_current_user
 from app.models.user import User
 from app.models.yield_domain import YieldDomain, YieldTransaction, YieldPayout, AffiliatePartner
-from app.config import settings
+from app.config import get_settings
+
+settings = get_settings()
 from app.schemas.yield_domain import (
     YieldDomainCreate,
     YieldDomainUpdate,