feat(studio): add stack traces to all error telemetry events

Send `stack_trace` (up to 4KB) on crash, unhandled_error, and
unhandled_promise_rejection events so PostHog captures the full JS
call stack for debugging. Also bump `component_stack` from 500→2000
chars, and add `error_name` to promise rejections.

packages/studio/src/components/StudioErrorBoundary.tsx

@@ -21,7 +21,8 @@ export class StudioErrorBoundary extends Component<Props, State> {
     trackStudioEvent("crash", {
       error_message: error.message,
       error_name: error.name,
-      component_stack: info.componentStack?.slice(0, 500) ?? null,
+      stack_trace: error.stack?.slice(0, 4000) ?? null,
+      component_stack: info.componentStack?.slice(0, 2000) ?? null,
     });
   }