add concurrent processing for visualization generation and update report streaming

move the "start new analysis button" to rop right corner to avoid confusion.

delete avatar image.

enhance viz code generation prompt

add history to chatbot and update solr query generation prompt errors. TODO: fix code generation for visualizations.

add solr data display to analysis flow and update yield statements for consistency

update field definitions for clarity and usage instructions in metadata and also prompt for better field_usage while facet generation.

remove unnecessary commented lines

remove unused sample_doc variable from solr_client search

update LLM model to 'gemini-2.5-flash'

delete unused available_fields

rollback to gemini-2.0-flash

Update app.py

trigger rebuild

test rebuild

Update app.py

Create app.py