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/core/config.py

@@ -14,6 +14,7 @@ This module focuses purely on configuration storage and validation.
 """
 
 from typing import List, Optional
+
 from pydantic_settings import BaseSettings
 
 
@@ -137,13 +138,9 @@ settings = Settings()
 # ENVIRONMENT UTILITIES - Module-level functions
 # =============================================================================
 # Import environment detection utilities
-from app.core.environment import (
-    get_environment,
-    is_development,
-    is_production,
-    is_staging,
-    should_use_secure_cookies
-)
+from app.core.environment import (get_environment, is_development,
+                                  is_production, is_staging,
+                                  should_use_secure_cookies)
 
 
 def get_current_environment() -> str:
@@ -190,6 +187,7 @@ def is_staging_environment() -> bool:
 # VALIDATION FUNCTIONS
 # =============================================================================
 
+
 def validate_production_settings() -> List[str]:
     """
     Validate settings for production environment.
@@ -243,22 +241,19 @@ def print_environment_info():
 # =============================================================================
 __all__ = [
     # Settings singleton
-    'settings',
-
+    "settings",
     # Environment detection (re-exported from app.core.environment)
-    'get_environment',
-    'is_development',
-    'is_production',
-    'is_staging',
-    'should_use_secure_cookies',
-
+    "get_environment",
+    "is_development",
+    "is_production",
+    "is_staging",
+    "should_use_secure_cookies",
     # Convenience functions
-    'get_current_environment',
-    'is_production_environment',
-    'is_development_environment',
-    'is_staging_environment',
-
+    "get_current_environment",
+    "is_production_environment",
+    "is_development_environment",
+    "is_staging_environment",
     # Validation
-    'validate_production_settings',
-    'print_environment_info',
+    "validate_production_settings",
+    "print_environment_info",
 ]