feat(panel): add a FAVORITED tab with a star on every recipe

src/utils/storageUtils.ts

@@ -3,6 +3,29 @@ import { Recipe } from '../types';
 import { DEFAULT_RECIPES, DEFAULT_ADJUSTMENTS } from './defaultRecipes';
 
 const CUSTOM_RECIPES_KEY = '@camrecipe_pro:custom_recipes';
+const FAVORITES_KEY = '@camrecipe_pro:favorites';
+
+// FAVORITED recipes: a list of recipe ids. Pure metadata — starring a recipe
+// never touches the look, so RESET and re-selecting a recipe leave it alone.
+export async function getFavoriteIds(): Promise<string[]> {
+  try {
+    const data = await AsyncStorage.getItem(FAVORITES_KEY);
+    if (!data) return [];
+    const parsed = JSON.parse(data);
+    return Array.isArray(parsed) ? parsed.filter((id) => typeof id === 'string') : [];
+  } catch (error) {
+    console.error('Failed to load favorites:', error);
+    return [];
+  }
+}
+
+export async function setFavoriteId(id: string, on: boolean): Promise<void> {
+  const ids = await getFavoriteIds();
+  const updated = on
+    ? [...new Set([...ids, id])]
+    : ids.filter((x) => x !== id);
+  await AsyncStorage.setItem(FAVORITES_KEY, JSON.stringify(updated));
+}
 
 export async function getCustomRecipes(): Promise<Recipe[]> {
   try {