add finish reason

[xzrderek]

Note

Adds finish reason capture to evaluation rows and surfaces necessary metadata for parsing.

• Adapter now parses raw_gen_ai_request OTEL span attributes to set execution_metadata.finish_reason (e.g., from llm.openai.choices)
• Proxy langfuse serializer includes observation metadata, enabling the adapter’s parsing logic
• Improves observations handling with or [] fallbacks; minor cleanup
• Remote server test config updated to ensure INFO logs; new assertions verify receipt of status logs and that finish_reason == "stop"

^{Written by Cursor Bugbot for commit b35c4bc. This will update automatically on new commits. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 3 potential issues.