docs(examples): add error handling example with retry strategies

[GustavoMori]

Description

Add comprehensive error handling example demonstrating common patterns for working with the Anthropic API.

What's included

• Error type hierarchy documentation
• Basic error handling with specific rescue blocks
• Built-in retry configuration (client and per-request)
• Custom exponential backoff with jitter
• Streaming error handling
• Circuit breaker pattern
• Graceful degradation strategies
• Logging and monitoring patterns
• Summary table of retryable vs non-retryable errors

Why

The SDK has robust error handling capabilities, but users lack practical examples showing common patterns. This example bridges that documentation gap.

Testing

• ruby -c examples/error_handling.rb - Syntax OK
• bundle exec rubocop examples/error_handling.rb - No offenses
• Example executes successfully

[rafael-pissardo]

👏

[GustavoMori]

Friendly ping.
Just checking if there's any feedback or changes needed from my side. Happy to adjust the implementation if necessary.