Refactor the streaming part.

[sebsto]

The new streaming code exposes the following elements

public enum ConverseStreamElement: Sendable {
    case messageStart(Role)  // start of a message
    case text(Int, String)  // partial text
    case reasoning(Int, String)  // partial reasoning
    case toolUse(Int, ToolUseBlock)  // a complete tool use response
    case messageComplete(Message)  // complete text message (with all content blocks and reason for stop)
    case metaData(ResponseMetadata)  // metadata about the response
}

[Copilot]

Pull Request Overview

This PR refactors the streaming layer to consolidate and simplify how SDK streaming events are translated into public ConverseStreamElement values. It removes legacy mock stream methods, introduces dedicated test stream generators, and overhauls ConverseReplyStream to use a buffered state machine with logging and new cases (text, reasoning, toolUse, metaData).

• Remove old mock implementations and add new package-scoped stream generators under Tests/ConverseStream
• Update ConverseStreamElement enum to new cases and add ResponseMetadata
• Rewrite ConverseReplyStream to convert raw SDK output into buffered state-driven elements with logging

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Tests/Mock/MockBedrockRuntimeClient.swift	Remove legacy mock stream methods
Tests/ConverseStream/MockBedrockRuntimeClient+StreamGenerator.swift	Add new package-scoped stream generators
Tests/ConverseStream/*.swift	Delete old vision/text/document tests, update tool/reasoning tests
Sources/Converse/Streaming/ToolUseStart.swift	Rename toolUseId to id, adjust initializers
Sources/Converse/Streaming/ResponseMetaData.swift	Introduce ResponseMetadata and nested types
Sources/Converse/Streaming/ConverseStreamElement.swift	Update enum cases (messageStart, text, reasoning, toolUse, metaData)
Sources/Converse/Streaming/ConverseReplyStream.swift	Rewrite stream conversion logic with buffered state, logging, and flush helper
Sources/Converse/Message.swift	Add StopReason, record stop reason in Message

Comments suppressed due to low confidence (1)

Tests/ConverseStream/ConverseStreamToolTests.swift:22

• [nitpick] The file name ConverseStreamToolTests.swift suggests tests for stream tooling, but it extends ConverseReplyStreamTests. Consider renaming the file or matching the extension target to keep names consistent.

extension ConverseReplyStreamTests {