sz_explorer: add generate command for full report export to CSV/HTML/JSON

[jbutcher21]

Summary

Add a generate command to sz_explorer that builds a complete report with all samples expanded and outputs to terminal, CSV, HTML, or JSON.

Syntax

generate audit_summary                              → display to terminal
generate audit_summary to results.csv               → CSV
generate audit_summary to results.html              → HTML
generate audit_summary merge to merge.csv           → filtered by category
generate data_source_summary CUSTOMERS to report.csv
generate cross_source_summary CUSTOMERS WATCHLIST

Format inferred from file extension. No file = display to terminal.

Supported reports

• audit_summary (with optional category filter: merge, split)
• data_source_summary (with optional data source filter)
• cross_source_summary (with optional data source filter)
• entity_size_breakdown
• entity_source_summary (with optional data source filter)

Design

• Each report builds an eda_table with all samples expanded
• eda_table gets new render_csv(), render_html(), render_json() methods using PrettyTable's built-in export
• Tab completion for report names, categories, and data sources