hook streaming first pass

[justschen]

adds specific hook part for rendering

cc @pwang347 @roblourens

[Copilot]

Pull request overview

This PR introduces a new chat progress “hook” part so hook execution results can be streamed from extensions, persisted in chat sessions, and rendered in the chat UI.

Changes:

• Adds proposed API surface for ChatResponseHookPart and a hookProgress(...) helper on ChatResponseStream.
• Extends the internal chat model/progress unions and session operation log schema to recognize the new kind: 'hook' part.
• Implements a new UI content part (ChatHookContentPart) and wires it into the chat list renderer.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/vscode-dts/vscode.proposed.chatParticipantAdditions.d.ts	Adds proposed API types + stream method for reporting hook execution results.
src/vs/workbench/contrib/chat/common/model/chatSessionOperationLog.ts	Updates persistence equality logic to account for the new hook part kind.
src/vs/workbench/contrib/chat/common/model/chatModel.ts	Adds hook to response/history unions and response stringification ignore list.
src/vs/workbench/contrib/chat/common/chatService/chatService.ts	Defines ChatHookType, ChatHookOutcome, and IChatHookPart and includes it in IChatProgress.
src/vs/workbench/contrib/chat/browser/widget/chatListRenderer.ts	Routes kind: 'hook' content to a dedicated renderer content part.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/media/chatHookContentPart.css	Styles hook outcome icon and hook detail display.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatHookContentPart.ts	Implements the collapsible hook result UI component.
src/vs/workbench/api/common/extHostTypes.ts	Adds ext host-side ChatResponseHookPart type for the API implementation.
src/vs/workbench/api/common/extHostTypeConverters.ts	Adds DTO conversions and part detection for ChatResponseHookPart.
src/vs/workbench/api/common/extHostChatAgents2.ts	Adds hookProgress(...) streaming method implementation in the ext host response stream.
src/vs/workbench/api/common/extHost.api.impl.ts	Exposes ChatResponseHookPart constructor on the proposed API object.