fix(logging): preserve ModelResponse choices format in redacted standard_logging_object + add Charity Engine provider endpoint

- Fix perform_redaction to handle dict representation of ModelResponse (from model_dump())
- Preserve full choices structure when redacting, redact content/audio in place
- Add _redact_standard_logging_object helper for standard_logging_object field
- Update test_logging_redaction_e2e_test assertions to expect choices format
- Add charity_engine to provider_endpoints_support.json

Fixes: test_standard_logging_payload, test_standard_logging_payload_audio
Made-with: Cursor

provider_endpoints_support.json

@@ -458,6 +458,24 @@
         "interactions": true
       }
     },
+    "charity_engine": {
+      "display_name": "Charity Engine (`charity_engine`)",
+      "url": "https://docs.litellm.ai/docs/providers/charity_engine",
+      "endpoints": {
+        "chat_completions": true,
+        "messages": true,
+        "responses": true,
+        "embeddings": false,
+        "image_generations": false,
+        "audio_transcriptions": false,
+        "audio_speech": false,
+        "moderations": false,
+        "batches": false,
+        "rerank": false,
+        "a2a": false,
+        "interactions": false
+      }
+    },
     "chutes": {
       "display_name": "Chutes (`chutes`)",
       "endpoints": {