Feature/error http status

[Pal-cloud]

Implements comprehensive HTTP error handling with custom error pages, middleware, and testing endpoints for improved user experience.

Key Features:

Error Handling Infrastructure

• New: error_handlers.py - Custom middleware for centralized error processing
• New: error_views.py - Dedicated views for HTTP error responses
• Updated: [settings.py]) - Logging configuration and error handling settings

Custom Error Templates:

• New directory: templates/error/ with responsive error pages:
  400.html, 403.html, 404.html, 500.html, error.html
  Professional, user-friendly error pages replacing Django defaults

Testing System:

• Preview endpoints for error page validation:
  /preview/400/, /preview/403/, /preview/404/, /preview/500/