docs(examples): add structured output example

[dhofheinz]

Summary

Adds a comprehensive example demonstrating how to produce structured JSON output using the tool_choice parameter. This addresses the documentation request in #816.

What This PR Does

• Adds examples/structured-output.ts with two complete examples:
  1. Non-streaming version: Shows how to force structured output and extract the result
  2. Streaming version: Demonstrates progressive structured output with delta handling

Key Feature Demonstrated

The critical pattern that enables structured output:

tool_choice: { type: 'tool', name: 'json' }

By defining a tool with the desired JSON schema and forcing its use via tool_choice, Claude returns guaranteed structured output matching the schema.

Examples Included

1. Vegetarian lasagna recipe - Generates ingredients list as structured JSON array
2. Paris landmarks - Demonstrates streaming structured output with location data

Additional Changes

The repository's formatter made minor whitespace improvements to:

• .github/workflows/create-releases.yml
• .github/workflows/release-docker.yml
• bin/cli

These are cosmetic-only changes that improve consistency.

Documentation

The example includes:

• Clear inline comments explaining the pattern
• Practical use cases
• Both streaming and non-streaming approaches
• Type-safe tool use block extraction

Fixes #816

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Note: This example demonstrates the workaround pattern mentioned in the issue, as the Anthropic API currently doesn't provide a first-class structured output feature. The tool_choice approach is the recommended method per the issue discussion.