feat(app): v2 desktop UI improvements (#29689)

Co-authored-by: Brendan Allan <git@brendonovich.dev>
Co-authored-by: Brendan Allan <14191578+Brendonovich@users.noreply.github.com>

packages/app/src/utils/toast.tsx

@@ -0,0 +1,34 @@
+import { Icon, type IconProps } from "@opencode-ai/ui/icon"
+import { Toast, showToast as showLegacyToast, type ToastOptions, type ToastVariant } from "@opencode-ai/ui/toast"
+import { ToastV2, showToastV2 } from "@opencode-ai/ui/v2/toast-v2"
+
+let v2 = false
+
+export function setV2Toast(value: boolean) {
+  v2 = value
+}
+
+export function ToastRegion(props: { v2: boolean }) {
+  if (props.v2) return <ToastV2.Region />
+  return <Toast.Region />
+}
+
+export function showToast(options: ToastOptions | string) {
+  if (!v2) return showLegacyToast(options)
+  if (typeof options === "string") return showToastV2(options)
+
+  return showToastV2({
+    ...options,
+    icon: resolveIcon(options.icon, options.variant),
+    actions: options.actions?.map((action) => ({
+      ...action,
+      variant: action.onClick === "dismiss" ? "secondary" : "primary",
+    })),
+  })
+}
+
+function resolveIcon(icon: IconProps["name"] | undefined, variant: ToastVariant | undefined) {
+  const name = icon ?? (variant === "success" ? "check" : undefined)
+  if (!name) return
+  return <Icon name={name} />
+}