Add DNS first-seen and last-seen history

[Lukas616]

No description provided.

[Lukas616]

Summary

Adds record history tracking to the JSON output:

• first-seen
• last-seen
• seen

It also adds the requested reporting options:

• --fs / --first-seen
• --ls <days>
• --lsd <MM/DD/YYYY>

Previously observed records are kept in the next JSON output even when they are not present in the latest run, so rotating records are not lost between runs.

Build compatibility

This also includes two small compatibility updates needed by current macOS/Homebrew builds:

• convert Beast field values to std::string without relying on removed .to_string() helpers
• include <string> where exception types use std::string

Checks

• Configured with CMake
• Built successfully
• Confirmed the new options appear in --help
• Ran a two-pass JSON check and confirmed seen increments, first-seen stays stable, and last-seen updates
• Ran a missing-record check and confirmed older records are retained and reported by --ls / --lsd

Payment can be sent here: https://paypal.me/Lukas61616