Debug panel fixes

[vijayupadya]

Fixes https://github.com/microsoft/vscode-internalbacklog/issues/6905, https://github.com/microsoft/vscode-internalbacklog/issues/6862

Fix 1: [object Object] in debug panel
extHostChatDebug.ts — typeof checks in the default fallback of _serializeEvent() to drop non-string name/details
chatDebugEventList.ts — safeStr() helper that returns '' for non-strings, with '(unknown)' fallback for name fields

Fix 2: Indefinite spinner for new sessions on home page
chatDebugHomeView.ts — Only show shimmer when the title is a UUID and no live model exists, not for new sessions that simply have no requests yet

[Copilot]

Pull request overview

This PR addresses two user-facing issues in the Chat Debug (Agent Debug Panel) UI: preventing [object Object] from appearing in debug event rows, and avoiding an indefinite loading shimmer/spinner for new sessions on the debug home page.

Changes:

• Gate the home view “shimmer” state on both UUID-like titles and absence of a live session model.
• Add string-sanitization in the debug event list rendering to avoid rendering non-string values as [object Object].
• Harden ext host event serialization fallback to drop non-string name/details for generic events.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/vs/workbench/contrib/chat/browser/chatDebug/chatDebugHomeView.ts	Adjusts shimmer logic so new/live sessions don’t show an indefinite spinner.
src/vs/workbench/contrib/chat/browser/chatDebug/chatDebugEventList.ts	Adds safeStr and uses it when rendering event name/details to avoid [object Object].
src/vs/workbench/api/common/extHostChatDebug.ts	Filters non-string name/details in the default serialization fallback.