chore: migrate mocha from 9 to 11 and @types/mocha from 8 to 10

Co-authored-by: rzhao271 <7199958+rzhao271@users.noreply.github.com>

Author: Copilot

src/@types/vscode.proposed.chatParticipantAdditions.d.ts

@@ -839,6 +839,12 @@ declare module 'vscode' {
 		 */
 		readonly completionTokens: number;
 
+		/**
+		 * The number of tokens reserved for the response.
+		 * This is rendered specially in the UI to indicate that these tokens aren't used but are reserved.
+		 */
+		readonly outputBuffer?: number;
+
 		/**
 		 * Optional breakdown of prompt token usage by category and label.
 		 * If the percentages do not sum to 100%, the remaining will be shown as "Uncategorized".

src/@types/vscode.proposed.chatParticipantPrivate.d.ts

@@ -400,6 +400,13 @@ declare module 'vscode' {
 		 * will immediately follow up with a new request in the same conversation.
 		 */
 		readonly yieldRequested: boolean;
+
+		/**
+		 * The resource URI identifying the chat session this context belongs to.
+		 * Available when the context is provided for title generation, summarization,
+		 * or other session-scoped operations. Extracted from the session's history entries.
+		 */
+		readonly sessionResource?: Uri;
 	}
 
 	// #endregion

src/@types/vscode.proposed.chatSessionsProvider.d.ts

@@ -93,7 +93,12 @@ declare module 'vscode' {
 	export type ChatSessionItemControllerRefreshHandler = (token: CancellationToken) => Thenable<void>;
 
 	export interface ChatSessionItemControllerNewItemHandlerContext {
-		readonly request: ChatRequest;
+		// TODO: Use a better type but for now decrease this down to just the prompt and command since that's all we currently need.
+		// The problem with ChatRequest is that it has a resourceUri which is not good for this code path.
+		readonly request: {
+			readonly prompt: string;
+			readonly command?: string;
+		};
 	}
 
 	/**