[observe] Add observe() example for Anthropic Claude

[nagasatish007]

Summary

Add an example script showing observe() wrapping an Anthropic Claude client.

What to do

• Create examples/observe-anthropic.ts and examples/observe_anthropic.py
• Wrap new Anthropic() with observe(), make one chat call, print getCost()
• Follow the same pattern as examples/observe-quickstart.ts

Example structure

import { observe } from 'tealtiger';
import Anthropic from '@anthropic-ai/sdk';

const client = observe(new Anthropic());

const response = await client.messages.create({
  model: 'claude-3-5-sonnet-20241022',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Hello Claude!' }],
});

console.log(response.content);
console.log(client.getCost());

Acceptance criteria

• TypeScript example runs locally
• Python example runs locally
• Both print cost summary
• No API key required for the PR review (mock or placeholder is fine in tests)
• README in examples folder updated to reference the new files

Helpful links

• Existing example: examples/observe-quickstart.ts
• Provider detector: src/observe/provider-detector.ts
• Anthropic SDK: https://github.com/anthropics/anthropic-sdk-node