Estimate nutrition based on the ingredient list

It'd be nice if the nutrition info was pre-calculated based on the ingredients list and some open nutrition database, for example openfoodfacts.org. One can potentially also add automatic categories/tags based on the ingredient list, like the dish being vegan, lactose-free or gluten-free.

If we can find a good match for each ingredient in the database the estimate can be filled in immediately. If for some ingredients there isn't a good product we can either pre-fill based on the ingredients we did recognize and highlight those we haven't found. I guess for ingredients we haven't found there's an opportunity to provide a list of entries there were found - an autocomplete of sorts.

At the moment the only other way I know how to compute nutrition is by hand, which gets annoying for recipes with a lot of ingredients.

The issue names no files, tests, or entry points; start by reviewing how recipe ingredients and nutrition are currently entered, since computation is currently done by hand. Define the Open Food Facts matching and fallback behavior, then verify estimates and automatic categories or tags for recognized and unrecognized ingredients.