[PP-4] Present all component instances that fail to render using toasts

Overview

Blocked on 📌 [PP-3] Server-rendered component instances failing to render should expose the meaningful error to the XB UI in a structured way Postponed .

#3518201 started exposing errors occurring during the rendering of a component tree via /xb/api/layout/….

Now it needs to be presented to the end user!

Proposed resolution

1. Render the structured information in the XB HTTP API response that #3518201 exposed to the client, using Radix UI Toasts.
2. Must include end-to-end test that verifies it works for 10 "broken" component instances.

ℹ️ This issue must spend ZERO time on visual tweaks — this will unblock the design work to happen for this! →

User interface changes

TBD