sessions: add telemetry for Agents window button interactions

[osortega]

Fixes https://github.com/microsoft/vscode-internalbacklog/issues/7256
Fixes https://github.com/microsoft/vscode-internalbacklog/issues/7257

Summary

Adds GDPR-compliant telemetry to track user interactions in the Agents window. All event types and logging helpers are centralized in a single file (sessionsTelemetry.ts), keeping call sites clean.

Event catalog

Titlebar buttons — vscodeAgents.interaction (button discriminator):

button	Location
newSession	sessionsView.ts:140
runPrimaryTask	runScriptAction.ts:199
addTask	runScriptAction.ts:245
generateNewTask	runScriptAction.ts:269
openTerminal	sessionsTerminalContribution.ts:325
openInVSCode	chat.contribution.ts:66

Changes panel — vscodeAgents.changesView/*:

Event	Data	Location
changesView/togglePanel	visible	changesTitleBarWidget.ts:195
changesView/versionModeChange	mode	changesView.ts:1838,1855,1872
changesView/viewModeChange	mode	changesView.ts:1756,1779
changesView/fileSelect	changeType	changesView.ts:1124
changesView/reviewCommentAdded	hasExistingFeedback, hasSuggestion, isFromPRReview	agentFeedbackService.ts:207

Already tracked via MenuWorkbenchButtonBar (telemetrySource: 'changesView' at changesView.ts:960):

• Merge Changes button + menu options
• Run Code Review button
• View All Changes button

Design

• src/vs/sessions/common/sessionsTelemetry.ts — single source of truth for all event types, classifications, and logging helpers
• Call sites import and call a one-liner helper (e.g. logSessionsInteraction(telemetryService, 'newSession')) instead of repeating publicLog2<…>(…) with inline type params

[Copilot]

Pull request overview

Adds a shared telemetry event (vscodeAgents.interaction) for top-level Agents window interactions, aiming to consistently capture which primary UI button/action users invoke across the Sessions (Agents) window surface.

Changes:

• Introduces shared telemetry event + classification types in src/vs/sessions/common/sessionsTelemetry.ts.
• Logs vscodeAgents.interaction for Agents window entry points: New Session, Run Primary Task, Add/Generate Task, Open Terminal, Open in VS Code.
• Wires telemetry into multiple contributions/actions that back the Agents window title-bar buttons.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/vs/sessions/contrib/terminal/browser/sessionsTerminalContribution.ts	Logs interaction telemetry when the “Open Terminal” title-bar action is invoked.
src/vs/sessions/contrib/sessions/browser/views/sessionsView.ts	Logs interaction telemetry when the “New Session” button is clicked.
src/vs/sessions/contrib/chat/browser/runScriptAction.ts	Logs interaction telemetry for “Run Primary Task”, “Add Task…”, and “Generate New Task…”.
src/vs/sessions/contrib/chat/browser/chat.contribution.ts	Logs interaction telemetry for the “Open in VS Code” action.
src/vs/sessions/common/sessionsTelemetry.ts	Adds shared event/classification type definitions for the new telemetry event.

Comments suppressed due to low confidence (1)

src/vs/sessions/contrib/chat/browser/chat.contribution.ts:82

• Telemetry is logged before confirming there is an active session and a resolvable folderUri, so interactions can be recorded even when the action immediately returns due to missing state. Consider moving the telemetry call to after the activeSession/folderUri checks.

	override async run(accessor: ServicesAccessor): Promise<void> {
		const telemetryService = accessor.get(ITelemetryService);
		telemetryService.publicLog2<SessionsInteractionEvent, SessionsInteractionClassification>('vscodeAgents.interaction', { button: 'openInVSCode' });

		const openerService = accessor.get(IOpenerService);
		const productService = accessor.get(IProductService);
		const sessionsManagementService = accessor.get(ISessionsManagementService);

		const activeSession = sessionsManagementService.activeSession.get();
		if (!activeSession) {
			return;
		}

		const workspace = activeSession.workspace.get();
		const repo = workspace?.repositories[0];
		const folderUri = activeSession.sessionType === CopilotCLISessionType.id ? repo?.workingDirectory ?? repo?.uri : undefined;

		if (!folderUri) {
			return;