Create multilingual form translation extraction toolkit

Build a CLI tool that extracts translatable strings from XLSForm or XForm files and produces a JSON locale file, making it easy to translate humanitarian forms into local languages.

Usage: npx extract-translations --input form.xlsx --output locales/form.json

Output format:

{
  formId: string,
  version: string,
  strings: {
    [key: string]: {
      default: string,      // original English text
      context: string,      // e.g. 'label for field: patient_age'
      translations: Record<string, string>  // { 'sw': '...', 'fr': '...' }
    }
  }
}

Key generation: stable hash of {fieldPath}:{stringType} where stringType is label, hint, or constraint_message. Using a stable key means re-extracting after form edits preserves existing translations for unchanged strings.

Merge mode: if an existing locale file is provided via --merge existing.json, preserve translations for unchanged strings and flag changed strings with { _changed: true, _previous: '...' }.

Support both XLSForm (parse with xlsx library) and XForm XML input.

Write tests with a sample XLSForm fixture covering: basic label extraction, hint extraction, merge with unchanged strings, merge with changed strings.