refactor: update display name format

[huang-benny]

Changed signal naming convention from parentheses to underscores, allowing signal names to be used as valid JavaScript object keys without quotes.

Previously, signal names like numberOfContributors(Maintenance) required quotes when used as object keys

signalScores: {
  MAINTENANCE: {
    'numberOfContributors(Maintenance)': 4, 
  }
}

Now with underscores, they work as valid identifiers:

signalScores: {
  MAINTENANCE: {
    numberOfContributors_Maintenance: 4,  // ✅ No quotes needed
  }
}

Changes

• Updated convertToDisplayName() to convert underscores to dashes for display
• Signal names now use underscores: numberOfContributors_Maintenance
• Display output uses dashes: Number Of Contributors - Maintenance

There are no other changes to the CLI input or output.