feat: offline save-for-later + background sync for mark-cooked (v0.65.0)

Adds a "Save offline" button on the recipe page that force-refetches
the current page so the service worker's cache picks up a fresh copy
right now, plus a small IndexedDB-backed list (lib/offline-db.ts) of
what's been saved. The /offline fallback page now reads that list and
renders it instead of being a dead end with just a "go back" link.

Also fixes the service worker's network-first fetch handler, which
never wrote successful responses into its cache -- meaning the
existing offline page's claim that "recently visited recipes are
available" was never actually true. It populates the cache on every
successful GET now.

Background sync: marking a batch-cook dish as cooked while offline
(the only existing mark-cooked call site in the app) now queues the
request in IndexedDB instead of just failing, and registers a
Background Sync (public/sw.js's "sync" listener replays the queue)
for Chromium; lib/offline-queue.ts's online-event fallback covers
Safari/Firefox, which never fire that event at all. Both replay paths
read/write the same IndexedDB store so either one drains it.

Also removes apps/web/public/manifest.json, a stale static manifest
that layout.tsx used to link to before the previous commit pointed it
at the real generated route (app/manifest.ts) -- it had gone
unnoticed and unused since.

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

apps/web/components/recipe/batch-cook-dishes.tsx

@@ -7,6 +7,7 @@ import { Snowflake, Refrigerator, ChefHat, Check } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { useLocale } from "@/lib/i18n/provider";
 import { stripMarkdown } from "@/lib/utils";
+import { queueOfflineAction } from "@/lib/offline-queue";
 
 type Dish = {
   id: string;
@@ -33,12 +34,31 @@ export function BatchCookDishes({ recipeId, dishes: initialDishes }: { recipeId:
 
   async function markCooked(dishId: string) {
     setMarkingId(dishId);
+    const body = { batchDishId: dishId, deductFromPantry: false };
     try {
-      const res = await fetch(`/api/v1/recipes/${recipeId}/cooked`, {
-        method: "POST",
-        headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ batchDishId: dishId, deductFromPantry: false }),
-      });
+      let res: Response;
+      try {
+        res = await fetch(`/api/v1/recipes/${recipeId}/cooked`, {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify(body),
+        });
+      } catch {
+        // fetch() throwing (rather than resolving with a non-ok status)
+        // means the network itself is unreachable — queue it for the
+        // service worker (or the online-event fallback) to replay later,
+        // rather than treating it as a real failure.
+        await queueOfflineAction({
+          method: "POST",
+          url: `/api/v1/recipes/${recipeId}/cooked`,
+          body,
+          description: `Mark dish ${dishId} as cooked`,
+        });
+        const now = new Date().toISOString();
+        setDishes((prev) => prev.map((d) => (d.id === dishId ? { ...d, cookedAt: now } : d)));
+        toast.info(t("batchCookMarkQueuedOffline"));
+        return;
+      }
       if (!res.ok) {
         toast.error(t("batchCookMarkFailed"));
         return;