feat(frontend): safe-area insets + hardened reduced-motion

- Add viewport export with viewportFit: "cover" so iOS exposes
  env(safe-area-inset-*) (required for the insets to take effect).
- NavRail / TopBar / main / Toaster now respect safe-area insets so content
  clears the iPhone notch and home indicator in both portrait and landscape.
- prefers-reduced-motion: the media query already disabled declared animation
  classes; harden it with a global transition/animation duration override and
  kill the scan-line shimmer so motion-sensitive users get a fully static UI.

Verified tsc --noEmit + next build clean.

services/frontend/src/components/primitives/toast.tsx

@@ -57,7 +57,7 @@ export function Toaster({ position = "bottom-right" }: { position?: string }) {
 
   const pos =
     position === "bottom-right"
-      ? "bottom-4 right-4"
+      ? "bottom-[calc(1rem+env(safe-area-inset-bottom))] right-[calc(1rem+env(safe-area-inset-right))]"
       : position === "top-right"
         ? "top-4 right-4"
         : "bottom-4 left-1/2 -translate-x-1/2";