Warn when view transitions run on a prefer-reduced-motion device

[martrapp]

Changes

In DEV mode, warn in the browser console when view transitions are used on a prefer-reduced-motion device.

A user at discord complained that view transitions wouldn't work at all, and @FredKSchott suggested that this could be the reason. Always fun to use an argument from authority!

Question: I would even like to remove the restriction that the warning is only shown in DEV mode as it is really hard to find. What do the approvers think?
Edit: (The warning is only shown with initial page loads, not on every view transition)

Testing

Manually tested on Windows with Chrome

Docs

Basically the warning message copies https://docs.astro.build/en/guides/view-transitions/#prefers-reduced-motion. So docs is more than up-to-date.

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[OliverSpeir]

Hmm ignoring in dev might be nice, but I assume there’s at least one dev who actually does want to prefer reduce motion for their own sake.

Could it be a config option ?

[martrapp]

Hmm ignoring in dev might be nice

Ah @OliverSpeir , I'm afraid, I didn't make myself clear: If someone has set up prefer-reduced-motion, we should definitely respect that. But I suspect that many developers only come across users who have set up their system this way in PROD. I therefore believe that the new warning message could also be useful in PROD.

[martrapp]

Might need a different text then: "This page was created with view transitions. Because your device ...." or similar. I'm usually the worst candidate to get English text right :)

[matthewp]

A lot of people will dislike logging happening in their frontend application. I think in dev mode it is ok, but wouldn't want it in prod.

[martrapp]

A lot of people will dislike logging happening in their frontend application. I think in dev mode it is ok, but wouldn't want it in prod.

Then fine with me as is.