feat: add design-doc-driven scan tests for §3.2, §3.3, §3.4, §3.6, §4.2

Based on 'Asset Scanning Support – SDK Design Document'.

New test sections added to assetScanStatus-test.js:

§ 3.2 Upload with param:
  - Upload response includes _asset_scan_status=pending when param passed
  - Upload response does NOT include status without param

§ 3.3 Download error handling:
  - SDK must surface asset_scan_pending/quarantined error codes (not swallow)
  - Download 422 errors must expose status + message to callers

§ 3.4 Publish is always async:
  - Publish returns success notice regardless of asset scan status
  - SDK must never throw asset_scan_quarantined synchronously on publish

§ 3.6 Legacy asset null handling:
  - null is a valid _asset_scan_status for pre-scan legacy assets
  - SDK must not convert null to undefined or crash on null status
  - Updated all list-query assertions to accept null per spec

§ 4.2 api_version header isolation:
  - After bulkOperation.publish({ api_version: '3.2' }), subsequent
    asset and content-type fetches must NOT carry api_version header
  - Regression guard against global header pollution

Author: aniket-shikhare-cstk

.talismanrc

@@ -4,5 +4,5 @@ fileignoreconfig:
 - filename: test/sanity-check/sanity.js
   checksum: f8b4b4b4492e04fd13338af9d99972807b4d61e2b0237a6c057d3f93d8c66d60
 - filename: test/sanity-check/api/assetScanStatus-test.js
-  checksum: 0b6afba5e427cd36aff0f09cd5540058b684cc728bc7ed9e08f6027dd80335bf
+  checksum: a79aac966542050091b7a979235ada0c700296f91ba28a0ab2d9e8109f56d6c3
 version: "1.0"