feat: add investigative source layer (OCCRP, DFRLab, Lighthouse Reports, The Sentry, GITOC, VSquare, Correctiv) (#3891)

* feat: add investigative source layer (OCCRP, DFRLab, Lighthouse Reports, The Sentry, GITOC, VSquare, Correctiv)

Adds 7 cross-border investigative outlets to INTEL_SOURCES with
type:'investigative'. All classified as 'intel' in SOURCE_TYPES.
Domains added to all 4 allowlist mirrors. Source tiers: OCCRP/DFRLab=2,
rest=3.

* fix: add missing comma after idp.nature.com in api allowlist (SyntaxError)

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Co-authored-by: zionappp-ui <zionappp-ui@users.noreply.github.com>
Co-authored-by: Elie Habib <elie.habib@gmail.com>