No screenshot in manifest, PWA install as app is not available

### Current Behavior

I tried to install dashboard as PWA on android, but i do not see the install as app option.
In chrome devTool => Application => Manifest , i have this warning :


It seems that there is a screenshot section missing in the manifest, which prevents me from installing the dasbboard as an application on android.

### Expected Behavior

Install app section available in chrome on android.
No warning for missing screenshot section in manifest.

### Steps To Reproduce

chrome devTool on dashboard => Application => Manifest

warning for screenshot missing

### Environment

- Dashboard version: 1.22.1
- Node-RED version: 4.0.9
- Node.js version: 20.18.3
- npm version: 10.8.2
- Platform/OS: ubuntu
- Browser: chrome

### Have you provided an initial effort estimate for this issue?

I am not a FlowFuse team member