refactor(pep8): enforce full PEP8 compliance across backend Python codebase

- ruff.toml: select E/W/F/I/N rules, line-length=120, drop legacy ignores
- Auto-fix: sort 82 import blocks (isort), remove 29 unused imports,
  strip 6 trailing-whitespace blank lines in docstrings
- main.py: move setup_logging and settings imports to top (E402)
- errors.py: noqa N818 on DDD exception names (96 call sites, safe)
- intel_service.py: noqa N817 for universal ET alias
- atomic/elastic/sigma import services: move _MAX_UNCOMPRESSED_SIZE and
  _MAX_ENTRIES to module level (N806)
- compliance_import_service.py: move SAMPLE_CONTROLS / CIS_CONTROLS to
  module level; wrap long description strings (N806 + E501)
- snapshot_service.py: move STATUS_ORDER dict to module level (N806)
- sigma_import_service.py: remove dead dedup_key expression (F841)
- threat_actor_import_service.py: remove dead stix_to_actor expression (F841)
- data_source.py, seed_demo.py, campaign_scheduler_service.py,
  lolbas_import_service.py: wrap lines exceeding 120 chars (E501)
- d3fend_import_service.py: per-file E501 ignore (data file with long strings)

All 439 unit tests pass. ruff check app/ → All checks passed!

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

backend/app/routers/campaigns.py

@@ -9,29 +9,51 @@ import uuid
 from typing import Optional
 
 from fastapi import APIRouter, Depends, Query
-from sqlalchemy.orm import Session
 from pydantic import BaseModel, Field
+from sqlalchemy.orm import Session
 
 from app.database import get_db
 from app.dependencies.auth import get_current_user, require_any_role
+from app.domain.unit_of_work import UnitOfWork
 from app.models.user import User
-from app.services.campaign_service import generate_campaign_from_threat_actor
+from app.services.audit_service import log_action
+from app.services.campaign_crud_service import (
+    activate_campaign as crud_activate,
+)
 from app.services.campaign_crud_service import (
     add_test_to_campaign as crud_add_test,
-    activate_campaign as crud_activate,
+)
+from app.services.campaign_crud_service import (
     complete_campaign as crud_complete,
+)
+from app.services.campaign_crud_service import (
     create_campaign as crud_create,
+)
+from app.services.campaign_crud_service import (
     get_campaign_detail as crud_get_detail,
+)
+from app.services.campaign_crud_service import (
     get_campaign_history as crud_get_history,
+)
+from app.services.campaign_crud_service import (
     get_campaign_progress_data as crud_get_progress,
+)
+from app.services.campaign_crud_service import (
     list_campaigns as crud_list,
+)
+from app.services.campaign_crud_service import (
     remove_test_from_campaign as crud_remove_test,
+)
+from app.services.campaign_crud_service import (
     schedule_campaign as crud_schedule,
+)
+from app.services.campaign_crud_service import (
     serialize_campaign,
+)
+from app.services.campaign_crud_service import (
     update_campaign as crud_update,
 )
-from app.domain.unit_of_work import UnitOfWork
-from app.services.audit_service import log_action
+from app.services.campaign_service import generate_campaign_from_threat_actor
 from app.services.notification_service import notify_role
 
 logger = logging.getLogger(__name__)