chore: ruff lint auto-fix — 9 errors fixed (import sorting, unused imports)

- I001: import block sorting in main.py, routes/__init__.py, companies.py, conftest.py, check_indexes.py
- F401: unused imports removed (asyncio, UTC, datetime, AsyncSession)
- 6 ASYNC240/230 warnings remain (os.path.exists in async, open() in test) — minor, non-blocking

scripts/check_indexes.py

@@ -22,7 +22,6 @@ from sqlalchemy.ext.asyncio import create_async_engine
 
 from app.config import get_settings
 
-
 # Required indexes for performance (table, index_name)
 REQUIRED_INDEXES = [
     ("contacts", "ix_contacts_tenant_deleted"),