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>

models/schema/marketplace_product.py

@@ -1,9 +1,12 @@
 # models/schema/marketplace_products.py - Simplified validation
 from datetime import datetime
 from typing import List, Optional
+
 from pydantic import BaseModel, ConfigDict, Field
+
 from models.schema.inventory import ProductInventorySummary
 
+
 class MarketplaceProductBase(BaseModel):
     marketplace_product_id: Optional[str] = None
     title: Optional[str] = None
@@ -45,27 +48,34 @@ class MarketplaceProductBase(BaseModel):
     marketplace: Optional[str] = None
     vendor_name: Optional[str] = None
 
+
 class MarketplaceProductCreate(MarketplaceProductBase):
-    marketplace_product_id: str = Field(..., description="MarketplaceProduct identifier")
+    marketplace_product_id: str = Field(
+        ..., description="MarketplaceProduct identifier"
+    )
     title: str = Field(..., description="MarketplaceProduct title")
     # Removed: min_length constraints and custom validators
     # Service will handle empty string validation with proper domain exceptions
 
+
 class MarketplaceProductUpdate(MarketplaceProductBase):
     pass
 
+
 class MarketplaceProductResponse(MarketplaceProductBase):
     model_config = ConfigDict(from_attributes=True)
     id: int
     created_at: datetime
     updated_at: datetime
 
+
 class MarketplaceProductListResponse(BaseModel):
     products: List[MarketplaceProductResponse]
     total: int
     skip: int
     limit: int
 
+
 class MarketplaceProductDetailResponse(BaseModel):
     product: MarketplaceProductResponse
     inventory_info: Optional[ProductInventorySummary] = None