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/main.py

@@ -9,7 +9,8 @@ This module provides:
 """
 
 from fastapi import APIRouter
-from app.api.v1 import admin, vendor, shop
+
+from app.api.v1 import admin, shop, vendor
 
 api_router = APIRouter()
 
@@ -18,31 +19,18 @@ api_router = APIRouter()
 # Prefix: /api/v1/admin
 # ============================================================================
 
-api_router.include_router(
-    admin.router,
-    prefix="/v1/admin",
-    tags=["admin"]
-)
+api_router.include_router(admin.router, prefix="/v1/admin", tags=["admin"])
 
 # ============================================================================
 # VENDOR ROUTES (Vendor-scoped operations)
 # Prefix: /api/v1/vendor
 # ============================================================================
 
-api_router.include_router(
-    vendor.router,
-    prefix="/v1/vendor",
-    tags=["vendor"]
-)
+api_router.include_router(vendor.router, prefix="/v1/vendor", tags=["vendor"])
 
 # ============================================================================
 # SHOP ROUTES (Public shop frontend API)
 # Prefix: /api/v1/shop
 # ============================================================================
 
-api_router.include_router(
-    shop.router,
-    prefix="/v1/shop",
-    tags=["shop"]
-)
-
+api_router.include_router(shop.router, prefix="/v1/shop", tags=["shop"])