Add nutrition per 100g and serving size in grams to the API

[kersten]

Is your feature request related to a problem? Please describe.
The API currently provides general nutrition values for one serving, which is useful, but it is difficult to compare recipes consistently or integrate them into nutrition tracking systems without values per 100 g. It is also hard to calculate exact nutrition for custom portion sizes when the serving weight in grams is not available.

Describe the solution you'd like
I would like the API to provide:

• nutrition values per 100 g
• serving size in grams, if available
• the existing per serving values can still remain

This would make the API much more useful for nutrition apps, food comparison, scaling portions, and detailed meal planning.

A possible structure could be something like:

• nutritionPerServing
• nutritionPer100g
• servingSizeGrams

Describe alternatives you've considered
An alternative would be to calculate per 100 g values manually from serving nutrition and serving size, but that only works if the serving size in grams is available. Without both values, downstream consumers have to guess or cannot calculate it reliably.

Additional context
This would be especially helpful for apps that track calories and macros in a standardized way, since per 100 g is a very common format for food data and makes recipe comparison much easier.