docs: def index():
      """Show the landing page."""
      gene_lists = app.db.gene_lists() if app.config['STORE_ENABLED'] else []
      queries = app.db.gemini_queries() if app.config['STORE_ENABLED'] else []
  
      case_groups = {}
      for case in app.db.cases():
          key = (case.variant_source, case.variant_type, case.variant_mode)
          if key not in case_groups:
              case_groups[key] = []
          case_groups[key].append(case)
  
      return render_template('index.html', case_groups=case_groups,
                             gene_lists=gene_lists, queries=queries)