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/services/lolbas_import_service.py

@@ -37,8 +37,8 @@ import requests as _requests
 import yaml
 from sqlalchemy.orm import Session
 
-from app.models.test_template import TestTemplate
 from app.models.data_source import DataSource
+from app.models.test_template import TestTemplate
 from app.services.audit_service import log_action
 
 logger = logging.getLogger(__name__)
@@ -176,7 +176,11 @@ def _parse_lolbas(root_dir: Path) -> list[dict]:
             results.append({
                 "mitre_technique_id": mitre_id,
                 "name": f"LOLBAS: {binary_name} — {usecase or cmd_description or mitre_id}"[:500],
-                "description": f"{description}\n\n{cmd_description}".strip()[:2000] if description else cmd_description[:2000] if cmd_description else None,
+                "description": (
+                    f"{description}\n\n{cmd_description}".strip()[:2000]
+                    if description
+                    else cmd_description[:2000] if cmd_description else None
+                ),
                 "source": "lolbas",
                 "platform": "windows",
                 "tool_suggested": binary_name,