fix: Restore parsed_exception access for backward compatibility

Reverted breaking change - parsed_exception is now accessible again.
This makes the changes purely additive with zero breaking changes.

What works (backward compatible):
- e.parsed_exception.code - Still works!
- e.parsed_exception.message - Still works!
- e.header.get('fga-request-id') - Still works!

What's new (additive):
- e.code - Convenience property
- e.error_message - Convenience property
- e.request_id - Convenience property
- e.store_id - Convenience property
- e.authorization_model_id - Convenience property
- e.operation_name - Auto-extracted from telemetry
- e.is_validation_error() - Helper method
- e.is_retryable() - Helper method
- etc.

Tests: 21 unit tests passing

Author: claude

openfga_sdk/exceptions.py

@@ -172,10 +172,7 @@ def __str__(self):
 
     @property
     def parsed_exception(self):
-        raise AttributeError(
-            "parsed_exception is not directly accessible. "
-            "Use e.code, e.error_message, e.request_id instead."
-        )
+        return self._parsed_exception
 
     @parsed_exception.setter
     def parsed_exception(self, content):