Minor memory leak fixes, maybe

[roblourens]

Ensure that the maps in the renderer like codeBlocksByEditorUri get cleared (surely these can go away somehow)

Mainly get rid of preceedingContentParts, I don't think this really fixes the issue since the getters on the context still retain a ref but it wasn't used anywhere else so might as well clean it up

[Copilot]

Pull request overview

This PR addresses potential memory leaks in the chat renderer by clearing maps when the view model changes and removing unnecessary object references that could prevent garbage collection.

Changes:

• Clear renderer maps (codeBlocksByEditorUri, codeBlocksByResponseId, fileTreesByResponseId, focusedFileTreesByResponseId) when view model is updated
• Remove preceedingContentParts from context interface and use local variables instead to avoid retaining references
• Extract element from context in ChatCollapsibleContentPart to avoid storing the entire context object

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
chatListRenderer.ts	Add map clearing in updateViewModel, remove preceedingContentParts from context objects, add treeStartIndex getter, and call clearRenderedParts in disposeTemplate
chatTreeContentPart.ts	Remove unused constructor parameters (element, treeDataIndex) and reorder imports
chatThinkingContentPart.ts	Replace this.context.element with this.element to use the extracted field
chatReferencesContentPart.ts	Replace this.context.element with this.element to use the extracted field
chatContentParts.ts	Remove preceedingContentParts property and add treeStartIndex property to interface
chatCollapsibleContentPart.ts	Extract element from context and store it as a field instead of storing the entire context object