FEAT-001: Add OnError callback to CsvReadOptions

[improveTheWorld]

Summary

Documentation implies OnError callback exists but it doesn't. Users need inline error handling.

Expected API

`csharp
var options = new CsvReadOptions {
ErrorAction = ReaderErrorAction.Skip,
OnError = (raw, ex) => errors.Add(ex)
};
``n

Current Workaround

Must use ErrorSink interface (more complex).

Recommendation

Add simple delegate: Action<string, Exception> OnError

Impact

• Aligns with 'make common cases easy' philosophy
• ErrorSink already exists for complex scenarios