feat: add ${sourceRoot} variable interpolation for NX workspaces

[shaharkazaz]

Summary

Adds support for ${sourceRoot} variable interpolation in output paths, enabling users to customize translation file locations across multiple apps/libs in NX workspaces using a single centralized configuration.

Problem (Issue #220)

When using transloco-keys-manager in NX monorepos, users want to:

• Use a single transloco.config.js at the workspace root
• Customize output paths (e.g., public/i18n instead of assets/i18n)
• Have paths resolve differently per project

Previously, setting output: '${sourceRoot}/../public/i18n' would create a literal ${sourceRoot} folder instead of interpolating the variable.

Solution

This PR implements variable interpolation for ${sourceRoot}:

Example configuration:

// transloco.config.js (workspace root)
module.exports = {
  langs: ['en', 'fr'],
  keysManager: {
    output: '${sourceRoot}/../public/i18n',
    scopePathMap: {
      admin: '${sourceRoot}/../public/i18n/admin'
    }
  }
};

Results in different paths per project:

• apps/my-app/public/i18n/en.json
• libs/my-lib/public/i18n/en.json

Changes

• ✅ Add ${sourceRoot} interpolation in resolveConfigPaths()
• ✅ Add __sourceRoot internal field to Config type
• ✅ Support interpolation in scopePathMap values via buildScopeFilePaths()
• ✅ Extract interpolation logic into interpolatePathFactory() helper
• ✅ Add comprehensive test coverage (20 new tests)
• ✅ Add NX workspace integration test simulating real-world scenario
• ✅ Fully backward compatible (existing configs work unchanged)

Test Coverage

New tests:

• __tests__/path.utils.spec.ts - 5 tests for buildScopeFilePaths() interpolation
• __tests__/resolveConfig/resolveConfig.spec.ts - 7 tests including NX workspace scenario

All 73 tests passing ✅

Backward Compatibility

✅ Fully backward compatible - paths without ${sourceRoot} work exactly as before

Fixes #220

[pkg-pr-new]

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npm i https://pkg.pr.new/jsverse/transloco-keys-manager/@jsverse/transloco-keys-manager@244

commit: 0db9b26