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/cooking-mode/cooking-mode.tsx

@@ -6,7 +6,7 @@ import { X, ChevronLeft, ChevronRight, List, Mic, MicOff, Play, Square, HelpCirc
 import { cn } from "@/lib/utils";
 import { useTranslations } from "next-intl";
 import { useLocale } from "@/lib/i18n/provider";
-import { hasQuantity } from "@/lib/fractions";
+import { formatIngredientQuantity, type UnitPref } from "@/lib/unit-conversion";
 import { useWakeLock } from "@/lib/hooks/use-wake-lock";
 
 type Step = { id: string; instruction: string; timerSeconds: number | null };
@@ -68,11 +68,13 @@ export function CookingMode({
   recipeTitle,
   steps,
   ingredients,
+  unitPref = "metric",
 }: {
   recipeId: string;
   recipeTitle: string;
   steps: Step[];
   ingredients: Ingredient[];
+  unitPref?: UnitPref;
 }) {
   const router = useRouter();
   const t = useTranslations("cookingMode");
@@ -342,7 +344,7 @@ export function CookingMode({
               {ingredients.map((ing, i) => (
                 <li key={i} className="text-sm flex gap-2">
                   <span className="text-muted-foreground shrink-0 w-16 text-right">
-                    {hasQuantity(ing.quantity) ? ing.quantity : ""}{ing.unit ? ` ${ing.unit}` : ""}
+                    {formatIngredientQuantity(ing.quantity, ing.unit, unitPref)}
                   </span>
                   <span>{ing.rawName}</span>
                 </li>