Parse agent and model separately from assistant header
- Added agent field to LogMessage and ParsedLogEntry
- Updated parser to split 'Agent · Model' header into two separate fields
- Agent now goes to 'Build' (or other agent name)
- Model now correctly captures 'glm-4.7' (or other model names)
- Added opencode.agent attribute to formatter and exporter
- Updated table format to show Agent and Model as separate columns
- gen_ai.model.name now correctly maps to actual model, not agent