Enhance image handling in chat attachments

[rebornix]

• Introduced coerceImageBuffer function to standardize image data handling.
• Updated ImageAttachmentWidget to utilize coerced image data for carousel display.
• Enhanced collectCarouselSections to merge request and response images.
• Added extractImagesFromChatRequest function for extracting user-attached images.
• Expanded test coverage for image extraction and carousel section collection.

Support image attachments in chat request in Image Carousel.

[Copilot]

Pull request overview

Adds support for showing user-attached images (from chat requests) in the Chat Image Carousel, alongside existing response/tool/inline-reference images.

Changes:

• Introduces coerceImageBuffer and extractImagesFromChatRequest to normalize and extract image attachment data from chat requests.
• Updates carousel section collection to merge request attachment images with response-derived images, including pending-request handling.
• Expands unit tests to cover request image extraction and carousel section collection behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/common/chatImageExtraction.ts	Adds request-image extraction and buffer coercion utilities.
src/vs/workbench/contrib/chat/browser/chatImageCarouselService.ts	Updates carousel section collection to include request attachments and pending requests.
src/vs/workbench/contrib/chat/browser/attachments/chatAttachmentWidgets.ts	Uses coerced image data and enables carousel opening for more attachment shapes.
src/vs/workbench/contrib/chat/test/common/chatImageExtraction.test.ts	Adds tests for extracting images from chat requests.
src/vs/workbench/contrib/chat/test/browser/chatImageCarouselService.test.ts	Adds tests for request/response merging and pending request sections.

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/browser/attachments/chatAttachmentWidgets.ts:460

• This condition enables pointer cursor + keyboard open handlers even when only imageData is present and the carousel feature is disabled, leading to a clickable UI that does nothing. Consider changing the condition to require either a resource, or (imageData && ImageCarouselEnabled) so interaction affordances match actual behavior.

		// Wire up click + keyboard (Enter/Space) open handlers
		if (resource || imageData) {
			this.element.style.cursor = 'pointer';
			this._register(registerOpenEditorListeners(this.element, async () => {
				await clickHandler();