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/exceptions/marketplace_product.py

@@ -4,7 +4,9 @@ MarketplaceProduct management specific exceptions.
 """
 
 from typing import Any, Dict, Optional
-from .base import ResourceNotFoundException, ConflictException, ValidationException, BusinessLogicException
+
+from .base import (BusinessLogicException, ConflictException,
+                   ResourceNotFoundException, ValidationException)
 
 
 class MarketplaceProductNotFoundException(ResourceNotFoundException):
@@ -34,10 +36,10 @@ class InvalidMarketplaceProductDataException(ValidationException):
     """Raised when product data is invalid."""
 
     def __init__(
-            self,
-            message: str = "Invalid product data",
-            field: Optional[str] = None,
-            details: Optional[Dict[str, Any]] = None,
+        self,
+        message: str = "Invalid product data",
+        field: Optional[str] = None,
+        details: Optional[Dict[str, Any]] = None,
     ):
         super().__init__(
             message=message,
@@ -51,10 +53,10 @@ class MarketplaceProductValidationException(ValidationException):
     """Raised when product validation fails."""
 
     def __init__(
-            self,
-            message: str,
-            field: Optional[str] = None,
-            validation_errors: Optional[Dict[str, str]] = None,
+        self,
+        message: str,
+        field: Optional[str] = None,
+        validation_errors: Optional[Dict[str, str]] = None,
     ):
         details = {}
         if validation_errors:
@@ -84,10 +86,10 @@ class MarketplaceProductCSVImportException(BusinessLogicException):
     """Raised when product CSV import fails."""
 
     def __init__(
-            self,
-            message: str = "MarketplaceProduct CSV import failed",
-            row_number: Optional[int] = None,
-            errors: Optional[Dict[str, Any]] = None,
+        self,
+        message: str = "MarketplaceProduct CSV import failed",
+        row_number: Optional[int] = None,
+        errors: Optional[Dict[str, Any]] = None,
     ):
         details = {}
         if row_number: