feat: cooking history/gallery, unit conversion, nutrition diary, pantry scan, digest cron, nutrition-targeted meal plans

Six M-sized items from HANDOFF.md's new-features backlog:

- Profile tabs: cooking-history stats (total cooked, last-cooked, streak)
  and a "cooked it" photo gallery, both owner-only
- Display-time unit conversion (metric<->imperial) for recipe ingredients,
  respecting each user's unitPref; original value always shown alongside
  the conversion
- Nutrition daily diary: per-day macro totals computed from cooking history
  x recipe nutritionData, compared against user goals
- Pantry scan: real barcode lookup (zxing + Open Food Facts, no API key)
  with an AI-vision fallback for unbarcoded items, always confirm-before-
  insert, both paths tier/rate-limited like other AI features
- Weekly digest email: new followers/comments/ratings + trending recipes,
  sent via a new `cron` Docker stage (alpine+crond+curl) and `digest-cron`
  compose service hitting a bearer-token-protected internal route
- Meal-plan generation can now target a user's nutrition goals as a
  prompt-level nudge (recipes are AI-invented, not DB-sourced, so this
  can't be a hard macro constraint)

Caught a real deploy-breaking issue while adding the cron stage: appending
it after `runner` silently changed the Dockerfile's default build target,
and `web`'s compose config didn't pin one — fixed by pinning `target:
runner` explicitly. Verified with typecheck, lint, and three separate
`docker build --target` runs (runner/cron/migrator) plus `docker compose
config` validation.

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

apps/web/components/recipe/serving-scaler.tsx

@@ -4,7 +4,7 @@ import { useState } from "react";
 import { useTranslations } from "next-intl";
 import { Minus, Plus, Sparkles, X } from "lucide-react";
 import { Button } from "@/components/ui/button";
-import { scaleQuantity, hasQuantity } from "@/lib/fractions";
+import { formatIngredientQuantity, type UnitPref } from "@/lib/unit-conversion";
 import { SubstituteIngredientPopover } from "@/components/recipe/substitute-ingredient-popover";
 
 type Ingredient = {
@@ -29,12 +29,14 @@ export function ServingScaler({
   recipeTitle,
   recipeId,
   onAiScale,
+  unitPref = "metric",
 }: {
   baseServings: number;
   ingredients: Ingredient[];
   recipeTitle?: string;
   recipeId?: string;
   onAiScale?: (ingredients: ScaledIngredient[] | null) => void;
+  unitPref?: UnitPref;
 }) {
   const t = useTranslations("servingScaler");
   const [servings, setServings] = useState(baseServings);
@@ -132,15 +134,15 @@ export function ServingScaler({
           .sort((a, b) => a.order - b.order)
           .map((ing) => {
             const aiIng = aiScaledIngredients?.find((s) => s.rawName === ing.rawName);
-            const scaled = scaleQuantity(ing.quantity, baseServings, servings);
             return (
               <li key={ing.id} className="flex gap-2 text-sm group">
                 <span className="font-medium tabular-nums min-w-[3rem] text-right">
                   {aiIng
-                    ? `${hasQuantity(aiIng.quantity) ? aiIng.quantity : ""}${aiIng.unit ? ` ${aiIng.unit}` : ""}`
-                    : scaled
-                      ? `${scaled}${ing.unit ? ` ${ing.unit}` : ""}`
-                      : ing.unit ?? ""}
+                    ? formatIngredientQuantity(aiIng.quantity, aiIng.unit, unitPref)
+                    : formatIngredientQuantity(ing.quantity, ing.unit, unitPref, {
+                        base: baseServings,
+                        desired: servings,
+                      })}
                 </span>
                 <span className="flex items-center gap-1">
                   {ing.rawName}