fix: serialize string info values as JSON

[barinali]

Proposed Changes

This pull request aims to fix the string serialization with JSON.stringify.

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[Copilot]

Pull request overview

Fixes how Zeebe variable info is derived from string atomicValue values by ensuring they are serialized as JSON string literals, preserving quotes and escaping control characters for UI/editor display.

Changes:

• Serialize string atomicValue values via JSON.stringify when computing variable.info.

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[nikku]

Please add a test case to assert the fix we implement. Code wise it looks ok, given that strings are now returned raw (without ticks).

[barinali]

Please add a test case to assert the fix we implement. Code wise it looks ok, given that strings are now returned raw (without ticks).

@nikku, I have #94 as the test pull request. Are there any specific test cases in your mind I should be incorporating?

[nikku]

Test coverage incorporated from #94 is great, thank you ⭐