Resolve linter contradictions: consolidate config, fix isort first-party, pylint 10/10

Agent-Logs-Url: https://github.com/christianlouis/dmarq/sessions/1e4a1f06-55b9-4040-853e-6aaf9ee574c8

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

backend/app/api/api_v1/endpoints/reports.py

@@ -1,11 +1,12 @@
 import logging
 from typing import List
 
+from fastapi import APIRouter, File, HTTPException, UploadFile, status
+from pydantic import BaseModel
+
 from app.services.dmarc_parser import DMARCParser
 from app.services.report_store import ReportStore
 from app.utils.domain_validator import DomainValidationError, validate_domain
-from fastapi import APIRouter, File, HTTPException, UploadFile, status
-from pydantic import BaseModel
 
 logger = logging.getLogger(__name__)