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/error_renderer.py

@@ -7,7 +7,7 @@ Handles fallback logic and context-specific customization.
 """
 import logging
 from pathlib import Path
-from typing import Optional, Dict, Any
+from typing import Any, Dict, Optional
 
 from fastapi import Request
 from fastapi.responses import HTMLResponse
@@ -114,7 +114,7 @@ class ErrorPageRenderer:
                 "error_code": error_code,
                 "context": context_type.value,
                 "template": template_path,
-            }
+            },
         )
 
         try:
@@ -129,8 +129,7 @@ class ErrorPageRenderer:
             )
         except Exception as e:
             logger.error(
-                f"Failed to render error template {template_path}: {e}",
-                exc_info=True
+                f"Failed to render error template {template_path}: {e}", exc_info=True
             )
             # Return basic HTML as absolute fallback
             return ErrorPageRenderer._render_basic_html_fallback(
@@ -228,7 +227,9 @@ class ErrorPageRenderer:
         }
 
     @staticmethod
-    def _get_context_data(request: Request, context_type: RequestContext) -> Dict[str, Any]:
+    def _get_context_data(
+        request: Request, context_type: RequestContext
+    ) -> Dict[str, Any]:
         """Get context-specific data for error templates."""
         data = {}
 
@@ -261,11 +262,19 @@ class ErrorPageRenderer:
 
             # Calculate base_url for shop links
             vendor_context = getattr(request.state, "vendor_context", None)
-            access_method = vendor_context.get('detection_method', 'unknown') if vendor_context else 'unknown'
+            access_method = (
+                vendor_context.get("detection_method", "unknown")
+                if vendor_context
+                else "unknown"
+            )
             base_url = "/"
             if access_method == "path" and vendor:
                 # Use the full_prefix from vendor_context to determine which pattern was used
-                full_prefix = vendor_context.get('full_prefix', '/vendor/') if vendor_context else '/vendor/'
+                full_prefix = (
+                    vendor_context.get("full_prefix", "/vendor/")
+                    if vendor_context
+                    else "/vendor/"
+                )
                 base_url = f"{full_prefix}{vendor.subdomain}/"
             data["base_url"] = base_url