feat: surface pantry-expiry recipe suggestions

Pantry page now shows a "Use it up soon" widget with recipes that use
soon-to-expire pantry items, across the user's own recipes plus public/
unlisted ones (the existing /recipes/can-cook page only looked at the
user's own). Extracted the matching/scoring logic shared by both into
lib/pantry-match.ts.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/pantry-match.ts

@@ -0,0 +1,40 @@
+export const EXPIRING_WITHIN_DAYS = 3;
+
+export function isExpiringSoon(expiresAt: Date | null): boolean {
+  if (!expiresAt) return false;
+  const days = Math.ceil((expiresAt.getTime() - Date.now()) / (1000 * 60 * 60 * 24));
+  return days >= 0 && days <= EXPIRING_WITHIN_DAYS;
+}
+
+type ScorableRecipe<T> = T & { ingredients: { rawName: string }[] };
+
+export function scoreRecipesAgainstPantry<T>(
+  recipesList: ScorableRecipe<T>[],
+  pantry: { rawName: string; expiresAt: Date | null }[]
+) {
+  const pantryKeys = new Set(pantry.map((p) => p.rawName.toLowerCase()));
+  const expiringSoonKeys = new Set(
+    pantry.filter((p) => isExpiringSoon(p.expiresAt)).map((p) => p.rawName.toLowerCase())
+  );
+
+  return recipesList
+    .filter((r) => r.ingredients.length > 0)
+    .map((recipe) => {
+      const matched = recipe.ingredients.filter((ing) => pantryKeys.has(ing.rawName.toLowerCase())).length;
+      const missing = recipe.ingredients
+        .filter((ing) => !pantryKeys.has(ing.rawName.toLowerCase()))
+        .map((ing) => ing.rawName)
+        .slice(0, 5);
+      const usesExpiring = recipe.ingredients
+        .filter((ing) => expiringSoonKeys.has(ing.rawName.toLowerCase()))
+        .map((ing) => ing.rawName);
+      const total = recipe.ingredients.length;
+      return { recipe, matched, total, pct: Math.round((matched / total) * 100), missing, usesExpiring };
+    })
+    .sort((a, b) => {
+      if (a.usesExpiring.length > 0 !== b.usesExpiring.length > 0) {
+        return a.usesExpiring.length > 0 ? -1 : 1;
+      }
+      return b.pct - a.pct;
+    });
+}