fix: use ipx for static builds instead of auto detect

[pi0]

Context: We discovered it with @atinux investigating broken nuxt UI docs since it was using vertical image optimization and not picked from.. Another story probably to solve for another day...

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When building Nuxt in static mode (nuxt generate) we assume everything is at build-time. Auto detected providers (vercel, amplify) only benefit for production deploys with a server running where as for a static deploy, we can save (dynamic optimization) costs and reduce issue surface by optimizing at build time.

This PR improves detectProvider internal utility to preserve auto-detected status and later use in nitro hook to switch back to ipx-static if needed (so user input is still respected)

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Latest commit:	14ee03f
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Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8701991) 68.20% compared to head (14ee03f) 68.22%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1224      +/-   ##
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+ Coverage   68.20%   68.22%   +0.01%     
==========================================
  Files          76       76              
  Lines        4299     4308       +9     
  Branches      397      398       +1     
==========================================
+ Hits         2932     2939       +7     
- Misses       1339     1340       +1     
- Partials       28       29       +1     

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[danielroe]

Actually, thinking about this I'm not 100% sure this is the right choice. Even with statically generated builds, we don't know that all images will be optimised at build time. (For example, they may be loading them in from an API.)

I think it's safer to have users opt-in to this behaviour.

rethinking

[pi0]

Vercel default config does not allow external URLs by default and we can detect this at build time using config if we want to allow this also automatically.

Build-time cost, is always less than on demand and we can use build-time caching and for staticly build-websites by default, we optimize only build-time images (again unless configured to allow external domain)

[danielroe]

The point is that we can optimise all images that are known at generate time, and for plenty of websites that is perfect 👌

But for websites that have any kind of dynamic image which might rely on the current behaviour, this would be a breaking change. That's why I'm suggesting it should be opt-in.