refactor(navigation): consolidate navigation with href helpers and extract push device hook

- Migrate all navigation calls from magic strings to centralized href helpers
- Extract inline device registration logic into useRegisterPushDevice hook
- Remove unused terms and privacy policy routes from profile stack
- Add hrefTradeDetail helper for trade detail navigation
- Restore routePayloadCache.stashSystemMessage for group request/invite handling
- Change desktop shell tab navigation from replace to push

src/app-navigation/AppDesktopShell.tsx

@@ -172,7 +172,7 @@ export function AppDesktopShell() {
 
   const handleTabChange = useCallback(
     (href: string) => {
-      router.replace(href);
+      router.push(href);
     },
     [router]
   );