fix: resolve lint errors in test files [CAR-932]

Fix 56 lint errors in test files that were blocking CI:
- E501: Split long SQL INSERT statements across multiple lines
- F401: Remove unused imports (os, unittest.mock.patch)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tests/test_auth/test_auth_endpoints.py

@@ -138,7 +138,8 @@ async def test_expired_session_rejected(client, db_engine):
     async with db_engine.begin() as conn:
         await conn.execute(
             text(
-                "INSERT INTO users (id, email, hashed_password, display_name, email_verified, created_at, updated_at) "
+                "INSERT INTO users (id, email, hashed_password, display_name, "
+                "email_verified, created_at, updated_at) "
                 "VALUES (:id, :email, :hp, :dn, :ev, :ca, :ua)"
             ),
             {