Add DNS first-seen and last-seen history

[clynbmilio]

Closes #1.

Summary

Adds DNS history tracking to the dataset:

• Stores first-seen, last-seen, and seen for DNS records.
• Preserves records that are no longer present in the latest scan.
• Tracks whether each record is currently observed.
• Adds --fs to report first-seen/current records on each run.
• Adds --ls <days> to report records missing from the latest scan and not seen within the provided day window.
• Adds --lsd <MM/DD/YYYY> to report records missing from the latest scan and not seen since a US-format date.
• Keeps backward-compatible loading for older datasets that do not have the new fields.

Also fixes build compatibility issues found while validating:

• Adds the missing Boost.Beast header conversion include.
• Adds missing <cstdint> includes for integer type usage.

Validation

• git diff --check
• Submodules initialized locally before build validation.
• Fork GitHub Actions build check passed:
  https://github.com/clynbmilio/dooked/actions/runs/27055020294

Bounty Payment

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