fix(security): prevent debug error pages on staging/production

Root cause: ExceptionHandlingInitializer attempted to autowire
EnvironmentType directly, but it was never registered in the DI
container. This caused the debug mode resolution to fail silently.

Changes:
- Use TypedConfiguration instead of EnvironmentType for proper DI
- Create ErrorHandlingConfig value object to centralize config
- Access debug mode via AppConfig.isDebugEnabled() which respects
  both APP_DEBUG env var AND EnvironmentType.isDebugEnabled()
- Register ErrorHandlingConfig as singleton in container
- Remove diagnostic logging from ResponseErrorRenderer

This ensures that staging/production environments (where
EnvironmentType != DEV) will not display stack traces, code context,
or file paths in error responses.

src/Framework/ExceptionHandling/Renderers/ResponseErrorRenderer.php

@@ -278,9 +278,6 @@ final readonly class ResponseErrorRenderer implements ErrorRenderer
         );
 
         $debugInfo = '';
-        // SECURITY FIX: Only show debug info in development mode
-        // Log to error_log for diagnostic purposes (can be removed after verification)
-        error_log("[ResponseErrorRenderer] isDebugMode={$this->isDebugMode}, APP_ENV=" . ($_ENV['APP_ENV'] ?? 'unknown'));
         if ($this->isDebugMode) {
             $debugInfo = $this->generateDebugSection($exception, $contextProvider);
         }