fix: ColorTheme type

[rindeal]

Partial is needed to support:

  const theme = {
    ...defaultOptions.colors!,
    ...options.colors
  };

The callable type then allows to use multiple stylings like bold+red, or even completely custom stylings.

Explicit Record type enforces strict typing for defaultTheme:

defaultTheme: Record<TokenType, Color>

After these changes, one could write a theme such as:

const createFormatter = (hex: string, bold = false) => {
  const r = parseInt(hex.slice(1, 3), 16);
  const g = parseInt(hex.slice(3, 5), 16);
  const b = parseInt(hex.slice(5, 7), 16);
  const colorCode = `\x1b[38;2;${r};${g};${b}m`;
  const boldCode = bold ? '\x1b[1m' : '';
  const resetCode = '\x1b[0m';
  return (str: string) => `${boldCode}${colorCode}${str}${resetCode}`;
};

const JSON_THEME: ColorTheme = {
  Whitespace: (str: string) => str,
  Brace: createFormatter('#ADD8E6'), // Light Blue
  Bracket: createFormatter('#ADD8E6'), // Light Blue
  Colon: createFormatter('#FF69B4'), // Hot Pink
  Comma: createFormatter('#FF69B4'), // Hot Pink
  StringKey: createFormatter('#FFA500', true), // Bold Orange
  StringLiteral: createFormatter('#00BFFF'), // Deep Sky Blue
  NumberLiteral: createFormatter('#FF4500'), // Orange Red
  BooleanLiteral: createFormatter('#FF4500', true), // Bold Orange Red
  NullLiteral: createFormatter('#FF4500', true), // Bold Orange Red
};