fix: group title on first ingredient + multi-site parser registry

- Fix ingredient groups creating empty entries in Mealie: set title
  field on the first ingredient after the group marker instead
- Refactor scraper with @_register decorator for URL-based site dispatch
- Update README with structured ingredients, groups, MEALIE_INTERNAL_URL

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/mealie.py

@@ -145,27 +145,26 @@ class MealieClient:
 
     def _build_payload(self, recipe: dict) -> dict:
         ingredients = []
+        pending_group = ""
         for item in recipe.get("ingredients", []):
             if isinstance(item, dict):
-                # Group header marker
+                # Group header marker — apply title to the next real ingredient
                 if "group" in item and "food" not in item:
-                    ingredients.append({
-                        "referenceId": str(uuid.uuid4()),
-                        "title": item["group"],
-                        "note": "",
-                        "isFood": False,
-                        "disableAmount": True,
-                    })
-                else:
-                    ingredients.append(self._build_ingredient(item))
+                    pending_group = item["group"]
+                    continue
+                ing = self._build_ingredient(item)
             else:
                 # Legacy: plain string
-                ingredients.append({
+                ing = {
                     "referenceId": str(uuid.uuid4()),
                     "note": str(item),
                     "isFood": False,
                     "disableAmount": True,
-                })
+                }
+            if pending_group:
+                ing["title"] = pending_group
+                pending_group = ""
+            ingredients.append(ing)
 
         instructions = []
         for text in recipe.get("instructions", []):