O3-4964: Refactor translation builder with per-language cache and merge priority

[Chinmay7070]

Requirements

• This PR has a title that briefly describes the work done including the ticket number. If there is a ticket, make sure your PR title includes a conventional commit label. See existing PR titles for inspiration.
• My work conforms to the OpenMRS 3.0 Styleguide and design documentation.
• My work includes tests or is validated by existing tests.

Summary

This PR refactors the Translation Builder to:

• Add per-language in-memory cache (localTranslations)
  to preserve user edits across language switches
• Add mergeTranslations(local, backend, fallback) utility
  function outside component with priority: local > backend > fallback
• Update handleUpdateValue to save edits to per-language cache
• Update languageChanger to check cache first before fetching backend
• Fix handleEditClick to remove duplicate setTranslations call

Screenshots

Related Issue

https://openmrs.atlassian.net/browse/O3-4964

Other

Testing

• Verified language switching preserves edits
• Verified backend fetch happens only once per language

[Chinmay7070]

Hi Everyone,
please review the PR when you get a chance?
Thank you!

[Chinmay7070]

hi @denniskigen , @NethmiRodrigo
please review the PR when you get a chance?
Thank you!