PageSpeed: add mobile/desktop strategy option

[dmythro]

The PageSpeed monitor currently calls the Google PageSpeed API without a strategy parameter, which defaults to desktop. There is no way to monitor mobile performance scores.

Mobile PageSpeed scores are typically lower and more representative of real-world user experience, since most web traffic is mobile. The ability to choose between mobile and desktop (or an option to monitor both) would make PageSpeed monitoring significantly more useful.

Suggested implementation

The Google PageSpeed API accepts a strategy parameter with values mobile or desktop:

https://pagespeedonline.googleapis.com/pagespeedonline/v5/runPagespeed?url=...&strategy=mobile

Options:

1. Add a strategy field to the PageSpeed monitor configuration (default: desktop for backward compatibility)
2. Or allow creating separate monitors for mobile and desktop

Reference

• PageSpeed API docs — strategy parameter
• Current implementation: server/src/service/infrastructure/network/PageSpeedProvider.ts

[dmythro]

Generally speaking, if I'd choose between mobile or desktop strategy — I'd take mobile for sure :)
But ideally we need to see both, sometimes comparison helps a lot in optimization.