Fix code formatting and linting issues

- Auto-format all Python files with black and isort
- Remove unused imports with autoflake
- Fix flake8 issues (missing newlines, blank lines, etc.)
- Fix nonlocal/global scope issues in main.py
- Fix security.py import order (E402)
- Remove f-string without placeholders
- Add nosec comment for intentional exception handling
- Fix test imports to match refactored DMARCParser API

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

backend/app/tests/test_api.py

@@ -1,10 +1,7 @@
-import pytest
-from fastapi import FastAPI
+from app.models.domain import Domain
 from fastapi.testclient import TestClient
 from sqlalchemy.orm import Session
 
-from app.models.domain import Domain
-
 
 def test_read_health(client: TestClient):
     """Test health check endpoint"""
@@ -30,11 +27,11 @@ def test_read_domains(client: TestClient, db_session: Session):
     domain2 = Domain(name="test.com", description="Test Domain", active=True)
     db_session.add_all([domain1, domain2])
     db_session.commit()
-    
+
     response = client.get("/api/v1/domains")
     assert response.status_code == 200
     data = response.json()
-    
+
     assert len(data) == 2
     assert {"name": "example.com", "description": "Example Domain"}.items() <= data[0].items()
     assert {"name": "test.com", "description": "Test Domain"}.items() <= data[1].items()
@@ -44,18 +41,18 @@ def test_create_domain(client: TestClient):
     """Test creating a new domain"""
     response = client.post(
         "/api/v1/domains",
-        json={"name": "newdomain.com", "description": "New Domain", "active": True}
+        json={"name": "newdomain.com", "description": "New Domain", "active": True},
     )
-    
+
     assert response.status_code == 201
     data = response.json()
     assert data["name"] == "newdomain.com"
     assert data["description"] == "New Domain"
     assert data["active"] is True
     assert "id" in data
-    
+
     # Check that the domain was actually created
     response = client.get("/api/v1/domains")
     assert response.status_code == 200
     domains = response.json()
-    assert any(d["name"] == "newdomain.com" for d in domains)
+    assert any(d["name"] == "newdomain.com" for d in domains)