Add PCI messaging PAN evidence fixtures

[DENGXUELIN]

/claim #1768

Summary

• Adds a Req 4.2.2 end-user messaging PAN evidence gate with PCI-PAN-MSG-01 through PCI-PAN-MSG-08.
• Requires channel inventory, DLP/input-control testing, content encryption evidence, raw storage/archive handling, scope impact, sampling, and cleanup workflow evidence before marking messaging channels in place or out of scope.
• Adds skill-local vulnerable and benign fixtures for policy-only support tickets with retained PAN versus secure payment-link routing with verified PAN blocking/redaction.

Validation

• git diff --check origin/main...HEAD
• git merge-tree --write-tree origin/main HEAD
• Markdown fence balance check
• Added-line ASCII check
• Marker check for PCI-PAN-MSG-01 through PCI-PAN-MSG-08 and version: "1.0.1"
• Added-line sensitive-pattern scan

Bounty

Requested tier: Improver Moderate / USD 100 if accepted.