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/app/(app)/recipes/[id]/page.tsx

@@ -12,6 +12,7 @@ import { DrinkPairingButton } from "@/components/recipe/drink-pairing-button";
 import { AdaptRecipeButton } from "@/components/recipe/adapt-recipe-button";
 import { PrintButton } from "@/components/recipe/print-button";
 import { ShareRecipeButton } from "@/components/recipe/share-recipe-button";
+import { SaveOfflineButton } from "@/components/recipe/save-offline-button";
 import { VersionHistoryButton } from "@/components/recipe/version-history-button";
 import { DeleteRecipeButton } from "@/components/recipe/delete-recipe-button";
 import { ForkRecipeButton } from "@/components/recipe/fork-recipe-button";
@@ -244,6 +245,7 @@ export default async function RecipePage({ params }: Params) {
             />
             <ForkRecipeButton recipeId={id} variant={isOwner ? "duplicate" : "fork"} />
             <ShareRecipeButton recipeId={id} visibility={recipe.visibility} />
+            <SaveOfflineButton recipeId={id} recipeTitle={recipe.title} />
             <PrintButton recipeId={id} />
             <ExportMarkdownButton
               markdown={recipeToMarkdown({