Document reviewed SecureString analyzer exceptions

[cmendesvdl]

Summary

• Add narrowly scoped, justified PSScriptAnalyzer suppressions for reviewed conversions that either persist immediately as DPAPI-protected blobs or construct in-memory PSCredentials for authentication.
• Mirror applicable suppressions across the legacy HotFix payload and synthetic standalone test harnesses.
• Refresh the packaged-file SHA256 manifest for the modified runtime files.

Validation

• DAT Pester suite: 59 passed, 0 failed.
• Modified PowerShell files: 9 parsed without errors.
• Targeted PSAvoidUsingConvertToSecureStringWithPlainText scan: 0 findings.
• FileHashes.md integrity check: all 20 entries match working-copy size and SHA256.