Refactor mapping of text labels and bone IDs

[leandrumartin]

🎯 Goal / Objective

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Important

Prerequisite issue: #352

Text annotations on an image can be clicked to navigate there. This is being handled by mapping the label text to a bone or bone part ID, in templates/js/imageAnnotationToDropdownMap.js. Preferably this would not be done in the front-end, though, so this mapping should be refactored to be stored directly in the data itself.

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✅ Tasks to be Completed

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Acceptance Criteria

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• The new feature is implemented as described.
• All related code passes the repository's workflow checks (linting, tests).
• The application runs without errors after the changes are made.
• (If applicable) New automated tests have been added to cover the changes.
• Any related documentation has been updated, including JSDoc comments or docstrings

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