Fix bugs and improve Table performance

[arzezak]

Summary

• Fix CLI to use passed argv instead of relying on global ARGV
• Memoize headers, columns, and column_widths in Table to avoid recomputation per row
• Fix headers deduplication for heterogeneous entries
• Raise error when CLI is invoked without a query
• Use lease_connection for Rails 7.2+ compatibility
• Add minitest/mock require for Ruby 4.0 compatibility