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/pantry/barcode-scanner.tsx

@@ -0,0 +1,69 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { useTranslations } from "next-intl";
+import { Loader2 } from "lucide-react";
+
+export function BarcodeScanner({
+  onDetected,
+  onError,
+}: {
+  onDetected: (barcode: string) => void;
+  onError?: (message: string) => void;
+}) {
+  const t = useTranslations("pantry");
+  const videoRef = useRef<HTMLVideoElement>(null);
+  const [starting, setStarting] = useState(true);
+  const detectedRef = useRef(false);
+
+  useEffect(() => {
+    let cancelled = false;
+    let controls: { stop: () => void } | null = null;
+
+    async function start() {
+      try {
+        const { BrowserMultiFormatReader } = await import("@zxing/browser");
+        const reader = new BrowserMultiFormatReader();
+        if (cancelled || !videoRef.current) return;
+
+        controls = await reader.decodeFromVideoDevice(
+          undefined,
+          videoRef.current,
+          (result) => {
+            if (result && !detectedRef.current) {
+              detectedRef.current = true;
+              onDetected(result.getText());
+              controls?.stop();
+            }
+          }
+        );
+        if (!cancelled) setStarting(false);
+      } catch (err) {
+        if (!cancelled) {
+          onError?.(err instanceof Error ? err.message : t("cameraError"));
+          setStarting(false);
+        }
+      }
+    }
+
+    void start();
+
+    return () => {
+      cancelled = true;
+      controls?.stop();
+    };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  return (
+    <div className="relative aspect-video w-full overflow-hidden rounded-lg bg-black">
+      <video ref={videoRef} className="h-full w-full object-cover" muted playsInline />
+      {starting && (
+        <div className="absolute inset-0 flex items-center justify-center bg-black/50">
+          <Loader2 className="h-6 w-6 animate-spin text-white" />
+        </div>
+      )}
+      <div className="pointer-events-none absolute inset-x-8 top-1/2 h-16 -translate-y-1/2 rounded-md border-2 border-white/70" />
+    </div>
+  );
+}