* Preserve optional content fields in PromptResultFormatter
The formatter's typed-content path rebuilt each Content object from only
its required fields, silently dropping everything else a prompt returned
(annotations on every type, _meta and explicit mimeType on embedded
resource contents). Delegate to the schema classes' fromArray() instead,
keeping the historical mimeType defaulting and RuntimeException-with-
index error contract.
ImageContent was the only content class without annotations support, so
it gains the same constructor/fromArray()/jsonSerialize() handling as
TextContent and AudioContent.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* Reword CHANGELOG entry to be user-facing
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Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
