fix(ruleset): ignore binary responses in collection array property rule

[sjh9714]

Summary

Fixes a false positive in ibm-collection-array-property for binary file responses.

What changed

• Added regression coverage for a list... operation returning application/pdf.
• Skipped collection array property validation for type: string, format: binary response schemas.
• Preserved existing validation for JSON collection responses.

Why

Issue #786 reports that PDF download endpoints are flagged as missing a collection array property even though they return binary files, not collections.

Testing

• npm run jest --workspace packages/ruleset -- test/rules/collection-array-property.test.js --runInBand
• npm run lint --workspace packages/ruleset
• npm run test-ruleset
• git diff --check

Fixes #786

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