style: apply black and isort formatting across entire codebase

- Standardize quote style (single to double quotes)
- Reorder and group imports alphabetically
- Fix line breaks and indentation for consistency
- Apply PEP 8 formatting standards

Also updated Makefile to exclude both venv and .venv from code quality checks.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/v1/vendor/settings.py

@@ -4,13 +4,14 @@ Vendor settings and configuration endpoints.
 """
 
 import logging
+
 from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_vendor_api
 from app.core.database import get_db
-from middleware.vendor_context import require_vendor_context
 from app.services.vendor_service import vendor_service
+from middleware.vendor_context import require_vendor_context
 from models.database.user import User
 from models.database.vendor import Vendor
 
@@ -20,9 +21,9 @@ logger = logging.getLogger(__name__)
 
 @router.get("")
 def get_vendor_settings(
-        vendor: Vendor = Depends(require_vendor_context()),
-        current_user: User = Depends(get_current_vendor_api),
-        db: Session = Depends(get_db),
+    vendor: Vendor = Depends(require_vendor_context()),
+    current_user: User = Depends(get_current_vendor_api),
+    db: Session = Depends(get_db),
 ):
     """Get vendor settings and configuration."""
     return {
@@ -44,10 +45,10 @@ def get_vendor_settings(
 
 @router.put("/marketplace")
 def update_marketplace_settings(
-        marketplace_config: dict,
-        vendor: Vendor = Depends(require_vendor_context()),
-        current_user: User = Depends(get_current_vendor_api),
-        db: Session = Depends(get_db),
+    marketplace_config: dict,
+    vendor: Vendor = Depends(require_vendor_context()),
+    current_user: User = Depends(get_current_vendor_api),
+    db: Session = Depends(get_db),
 ):
     """Update marketplace integration settings."""
     # Verify permissions