feat: add gradient and theme features with corresponding tests and documentation

examples/gradient.js

@@ -0,0 +1,39 @@
+import chalk from '../source/index.js';
+
+// Set color level to enable gradients (adjust based on terminal support)
+chalk.level = 3;
+
+// Demonstrate gradient feature
+console.log(chalk.bold('Chalk Gradient Examples'));
+console.log();
+
+// Simple two-color gradient
+console.log('Two-color gradient:');
+console.log(chalk.gradient('#ff0000', '#0000ff')('Hello World'));
+console.log();
+
+// RGB array gradient
+console.log('RGB array gradient:');
+console.log(chalk.gradient([255, 0, 0], [0, 255, 0], [0, 0, 255])('Rainbow Text'));
+console.log();
+
+// Multi-color gradient
+console.log('Multi-color gradient:');
+console.log(chalk.gradient('#ff0000', '#ffff00', '#00ff00', '#00ffff', '#0000ff')('Color Spectrum'));
+console.log();
+
+// Combining with other styles
+console.log('Gradient with bold:');
+console.log(chalk.gradient('#ff0080', '#8000ff').bold('Bold Gradient'));
+console.log();
+
+// Gradient on themed chalk
+const themedChalk = chalk.theme({
+	rainbow: chalk.gradient('#ff0000', '#ffff00', '#00ff00', '#00ffff', '#0000ff'),
+});
+
+console.log('Themed gradient:');
+console.log(themedChalk.rainbow('Themed Rainbow Text'));
+console.log();
+
+console.log(chalk.bold('Gradient Complete!'));