fix: export-jdl preserves destination-side relationship annotations

[trifonnt]

Summary

• Destination-side relationship annotations were lost during export-jdl because getDestinationEntitySideAttributes() never extracted options from the matched right-side relationship
• Now extracts and maps destination relationship options into JDLRelationship.options.destination

Example

JDL example that demonstrates the fix:

// Before the fix, @CustomTag annotation was lost during export-jdl round-trip

entity Author {
  name String
}
entity Book {
  title String
}
relationship OneToMany {
  Author{book} to @CustomTag Book{author}
}

The @CustomTag on the destination side (Book) would be silently dropped when running jhipster export-jdl. After the fix, it is now preserved.

Closes #32655

Test plan

• Added unit test for destination-side relationship options in json-to-jdl-entity-converter.spec.ts
• Added options: { destinationAnnotation: true } to right-side relationship in export-jdl.spec.ts
• All 30 tests passing, snapshots updated

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[Copilot]

Pull request overview

This PR fixes export-jdl so that relationship annotations/options defined on the destination (right) side of a bidirectional relationship are preserved when converting JSON entities back into JDL.

Changes:

• Extract destination-side relationship options from the matched right-side relationship entry.
• Map those extracted options into JDLRelationship.options.destination during JSON → JDL conversion.
• Extend unit/integration coverage and update snapshots to assert destination-side annotations appear in exported JDL.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
lib/jdl/converters/json-to-jdl-entity-converter.ts	Maps right-side relationship options into JDLRelationship.options.destination when constructing the merged relationship.
lib/jdl/converters/json-to-jdl-entity-converter.spec.ts	Adds a unit test asserting destination-side relationship options are parsed into options.destination.
generators/export-jdl/export-jdl.spec.ts	Adds options to a right-side relationship fixture to validate end-to-end behavior.
generators/export-jdl/snapshots/export-jdl.spec.ts.snap	Updates snapshots to confirm destination annotations render on the destination entity side in the exported JDL.

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