feat: add recipe and OpenFoodFacts search to nutrition food search

Recipes from /rezepte now appear in the food search on /fitness/nutrition,
with per-100g nutrition computed server-side from ingredient mappings.
Recipe results are boosted above BLS/USDA/OFF in search ranking.

OpenFoodFacts products are now searchable by name/brand via MongoDB
text index, alongside the existing barcode lookup.

Recipe and OFF queries run in parallel with in-memory BLS/USDA scans.

src-tauri/Cargo.lock

@@ -144,7 +144,7 @@ dependencies = [
 
 [[package]]
 name = "bocken"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "serde",
  "serde_json",