StreamAccumulator never set its model field, so
Response().Model was always empty for streamed
completions. Add a Model field to stream events
and populate it in all three providers (OpenAI,
Anthropic, Bedrock).
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
Incrementing toolIndex on every ContentBlockStop caused it to drift
when non-tool blocks (e.g. text) preceded tool-use blocks, making
Bedrock tool calls disappear from the accumulated response.
Track whether the current content block is a tool-use block and only
bump the index when a tool-use block ends.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
