chore: Improve handling of custom ORD content

[mlakov]

Refactor Custom ORD Content Merging with Strategy-Based Approach

Refactor

♻️ Replaced the generic object traversal merge logic for custom ORD content with an explicit, strategy-based approach using a MERGE_STRATEGIES map. This improves correctness, predictability, and eliminates the need for workarounds like cleanNullProperties.

Changes

• lib/extend-ord-with-custom.js: Major refactor of the merging logic:

  • Removed cleanNullProperties and the old patchGeneratedOrdResources functions.
  • Introduced a MERGE_STRATEGIES map defining explicit per-property merge behavior (scalar replace, object assign, or smart array merge by key).
  • Added prune helper to remove null/undefined values from merged entities.
  • Added merge helper for smart array-of-objects merging using configurable identity keys (e.g., ordId, groupId).
  • getCustomORDContent now consistently returns {} instead of undefined when no custom file is configured or the file is missing.
  • compareAndHandleCustomORDContentWithExistingContent now uses the strategy map to handle properties exclusive to either side or present in both.
  • Removed the warning for top-level primitive properties — they are now handled via the strategy map.
  • Removed the CONTENT_MERGE_KEY dependency from constants.

• __tests__/unit/extend-ord-with-custom.test.js: Updated test descriptions and expectations to reflect {} return values instead of undefined; removed the deprecated "warn on top-level primitive" test case.

• __tests__/bookshop/ord/custom.ord.json: Removed conflicting top-level properties (namespace, openResourceDiscovery) that were only needed for the now-removed warning test.

• __tests__/unit/__snapshots__/extend-ord-with-custom.test.js.snap: Updated snapshots to reflect the removal of the deprecated test case and corrected localId values.

• __tests__/unit/__snapshots__/ord.e2e.test.js.snap: Updated snapshots to reflect corrected ordering and content of merged packages, including fixed shortDescription and version values from the improved merge strategy.

• 🔄 Regenerate and Update Summary

PR Bot Information

Version: 1.20.51

• Event Trigger: issue_comment.edited
• Correlation ID: 6c3ac90f-9ddf-4fa7-ae63-ac5685b83b3a

[mlakov]

@zongqichen, @swennemers - can you, please, review ?

[zongqichen]

LGTM