fix(copyright): recover bounded POD author credits

[mstykow]

Summary

• Recover contact-backed author identities from bounded POD AUTHOR and AUTHORS sections.
• Treat POD headings, block directives, blank lines, and a 4 KiB paragraph cap as structural boundaries.
• Normalize common role-prefixed and email-first roster forms while excluding operational and copyright contacts.

Issues

• Covers: follow-up author-detection gaps found while validating False-positives when comparing provenant with scancode-toolkit output #1391

Scope and exclusions

• Included: contact-backed POD author paragraphs, multi-author paragraphs, wrapped contacts, role-prefixed rosters, late-phase value deduplication.
• Explicit exclusions: contactless POD credits and unstructured header comments; those require separate evidence rules.

How to verify

• Scan Perl 5.38.4 with --copyright and compare author values against the parent branch. This branch adds 430 author values across 265 files, removes none, and leaves copyright and holder values unchanged.
• Scan Info-ZIP 3.0 with --copyright; author, copyright, and holder output should be exactly unchanged from the parent branch.

Intentional differences from Python

• ScanCode has author output in only 48 of the affected Perl files and exactly matches 12 recovered values. Provenant uses the explicit POD section contract to recover more source-faithful identities while retaining hard section and size bounds.

Follow-up work

• Created or intentionally deferred: recover contactless names and collectives from the same bounded POD sections in a separately benchmarked stack layer.

Expected-output fixture changes

• Files changed: none.
• Why the new expected output is correct: focused end-to-end tests cover the new extraction and boundary behavior without altering existing golden fixtures.

[mstykow]

@greptileai review