example: add example for image input understanding

[princeaden1]

Summary

This PR introduces an example for using image inputs with the Anthropic client. It enables multimodal functionality where the model can understand and respond to image-based prompts alongside text.

Changes

• Extended client to accept image files as input (e.g., via fs.createReadStream)
• Added example usage in examples/images.ts demonstrating how to send an image prompt

Usage

const filePath = path.join(__dirname, 'logo.png');
  const buffer = fs.readFileSync(filePath);
  const base64Image = buffer.toString('base64');
  const result = await client.messages.create({
    messages: [
      {
        role: 'user',
        content: [
          {
            type: 'text',
            text: 'What is in this image?',
          },
          {
            type: 'image',
            source: {
              data: base64Image,
              type: 'base64',
              media_type: 'image/png',
            },
          },
        ],
      },
    ],
    model: 'claude-sonnet-4-20250514',
    max_tokens: 1024,
  }); ```