make chat thinking stream screen reader accessible

[meganrogge]

fixes #286777

Adds a ChatThinkingAccessibleView, which can be accessed via a command. If no thinking is present, we alert to indicate that. Otherwise, we open the accessible view with the current thinking content.

Uses shift+alt+f2 to align with and extend the existing alt+f2 one.

• to discuss with screen reader users: should we clear the thinking content once thinking has stopped or leave it around until the next thinking stream comes in?

[Copilot]

Pull request overview

This PR adds accessibility support for "thinking" content in chat responses. It creates a new accessible view that allows screen reader users to access the AI's thinking process during chat interactions.

Changes:

• New ChatThinkingAccessibleView class to provide accessible view support for thinking content
• Registration of the new accessible view in the contribution registry
• Added ChatThinking enum value to AccessibleViewProviderId

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/vs/workbench/contrib/chat/browser/accessibility/chatThinkingAccessibleView.ts	New accessible view implementation that extracts and presents thinking content from chat responses
src/vs/workbench/contrib/chat/browser/chat.contribution.ts	Imports and registers the new ChatThinkingAccessibleView
src/vs/platform/accessibility/browser/accessibleView.ts	Adds ChatThinking provider ID to the enum

[meganrogge]

@justschen not familiar with the thinking streaming, so pls lmk if i'm doing something wrong or if there's a better way to get the content 😄

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

[justschen]

thanks!!