Enhance OpenBrainMap as a Progressive Web App (PWA)

To provide users with an improved experience, we should optimize OpenBrainMap as a Progressive Web App (PWA). This optimization includes implementing service workers for offline access, adding a manifest file for installation on mobile devices, and optimizing performance for faster loading and responsiveness.

In addition, we need to design a visually appealing app icon that aligns with the branding of OpenBrainMap. Furthermore, it's essential to address the issue where the title bar of the app is partially obscured by the iPhone notch, ensuring that the user interface is properly displayed on devices with notches.

The issue names no files, tests, or entry points, so first map the existing web application structure and identify where startup, assets, and layout are handled. Define separate acceptance checks for offline access, installability, loading performance, the app icon, and correct display around iPhone notches.

Written by the indexing model from the issue text.