This commit implements the design document for splitting the monolithic ResearchState into separate, named artifacts with custom visualizations. Major changes include:

## New Artifact Classes
- **QueryContext**: Immutable context containing the research query and sub-questions
- **SearchData**: All search results and cost tracking information
- **SynthesisData**: Synthesized information from searches (including enhanced versions)
- **AnalysisData**: Cross-viewpoint analysis and reflection metadata
- **FinalReport**: The generated HTML report with metadata

## Custom Materializers
Each artifact now has its own materializer with beautiful HTML visualizations:
- Interactive charts using Chart.js for search costs
- Collapsible sections for better organization
- Consistent styling across all artifact views
- Metadata tables with key statistics

## Pipeline Updates
- All steps refactored to use the new artifact-based approach
- Proper dependencies established between parallel steps
- Fixed merge step to run after parallel sub-question processing
- Updated metadata logging and tagging throughout

## Bug Fixes
- Fixed log_metadata calls to include infer_artifact=True parameter
- Fixed template variable names in final report generation
- Corrected enhanced_info merging logic to preserve original synthesis data
- Added proper step dependencies in parallel pipeline

## Test Updates
- Updated all tests to use the new artifact-based interface
- Tests now create individual artifacts instead of ResearchState
- Maintained test coverage for all functionality

This refactoring improves modularity, enables better artifact visualization in the ZenML dashboard, and makes the pipeline more maintainable and extensible.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>