Native botification modules for macOS and Windows

## Context

After researching existing React Native notification libraries, we found limited support for desktop platforms. Most libraries like `react-native-toast-message` and `react-native-toast-notifications` focus on mobile, while `react-native-rooster` (the only cross-platform option) didn't work correctly in our tests.

We prefer a reliable, dependency-free solution for displaying toast notifications.

Slack thread with more context: https://infinitered.slack.com/archives/C22K52MK2/p1760587029746029

Also, Lizzi [suggested](https://infinitered.slack.com/archives/C22K52MK2/p1760657146028209?thread_ts=1760587029.746029&cid=C22K52MK2) it'd be worth reaching out to the React Native Windows team, since they've worked on building out design system components for Microsoft.

## Proposal

Create native modules for both macOS (using Swift/Objective-C with NSUserNotificationCenter) and Windows (using C++/WinRT with Windows.UI.Notifications). This approach would give us full control over the notification behavior and positioning, similar to successful implementations in VS Code (bottom-right) and Raycast (minimal, native-styled).

The modules should support basic toast functionality with customizable duration, positioning, and action buttons while maintaining platform-specific UI conventions.

No files, tests, or entry points are named. Start by locating the React Native desktop module structure, then review the proposed NSUserNotificationCenter and Windows.UI.Notifications approaches. Done means native macOS and Windows toast modules support duration, positioning, and action buttons with platform-specific behavior.

Written by the indexing model from the issue text.