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>

tests/performance/test_api_performance.py

@@ -28,7 +28,9 @@ class TestPerformance:
 
         # Time the request
         start_time = time.time()
-        response = client.get("/api/v1/marketplace/product?limit=100", headers=auth_headers)
+        response = client.get(
+            "/api/v1/marketplace/product?limit=100", headers=auth_headers
+        )
         end_time = time.time()
 
         assert response.status_code == 200
@@ -54,7 +56,9 @@ class TestPerformance:
 
         # Time search request
         start_time = time.time()
-        response = client.get("/api/v1/marketplace/product?search=Searchable", headers=auth_headers)
+        response = client.get(
+            "/api/v1/marketplace/product?search=Searchable", headers=auth_headers
+        )
         end_time = time.time()
 
         assert response.status_code == 200
@@ -115,7 +119,8 @@ class TestPerformance:
         for offset in offsets:
             start_time = time.time()
             response = client.get(
-                f"/api/v1/marketplace/product?skip={offset}&limit=20", headers=auth_headers
+                f"/api/v1/marketplace/product?skip={offset}&limit=20",
+                headers=auth_headers,
             )
             end_time = time.time()