feat: preferences, exclusion-aware planner, /onboarding (PRD §5.1, §3)

Preferences (PRD §5.1)
- @ketopath/shared: zod schemas + EXCLUSION_GROUPS, CUISINE_TAGS,
  COOKING_TIMES, FASTING_PROTOCOL_VALUES
- apps/api: GET/PATCH /me/preferences (exclusions, cuisinePreferences,
  cookingTime, fastingProtocol)
- apps/web: PreferencesForm chip-based + PreferencesSection wired into
  /profile so existing users can edit
- Plan generation now aggregates Ingredient.exclusionGroups → Recipe
  exclusionTags so matchMeals filters out excluded recipes

Onboarding (PRD §3)
- /onboarding multi-step (profile → preferences → done) with smart-jump:
  starts at the first incomplete step
- ProfileForm gains optional onSaved/saveLabel for reuse outside /profile
- Redirect chain updated: /welcome accept → /onboarding (was /profile);
  /plan, /tracking, /shopping redirect missing profiles to /onboarding
- /profile remains the editing surface for returning users

i18n
- New Onboarding + Preferences namespaces (it)

Smoke tested end-to-end: selected fish exclusion, regenerated the plan,
verified Salmone/Branzino/Tonno are filtered out and unaffected recipes
(Frittata, Pollo, Mandorle, Polpette) remain.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/app/[locale]/onboarding/page.tsx

@@ -0,0 +1,70 @@
+import { prisma } from '@ketopath/db';
+import { redirect } from 'next/navigation';
+import { useTranslations } from 'next-intl';
+import { setRequestLocale } from 'next-intl/server';
+
+import { Masthead } from '@/components/masthead';
+import { getServerSession } from '@/lib/auth';
+
+import { fetchProfile } from '../profile/actions';
+import { fetchPreferences } from '../profile/preferences-actions';
+import type { ProfileForm } from '../profile/profile-form';
+
+import { OnboardingFlow } from './onboarding-flow';
+
+export default async function OnboardingPage({
+  params: { locale },
+}: {
+  params: { locale: string };
+}) {
+  setRequestLocale(locale);
+  const session = await getServerSession();
+  if (!session?.user) redirect('/sign-in');
+
+  const user = await prisma.user.findUnique({
+    where: { id: session.user.id },
+    select: { disclaimerAcceptedAt: true },
+  });
+  if (!user?.disclaimerAcceptedAt) redirect('/welcome');
+
+  const [profile, preferences] = await Promise.all([fetchProfile(), fetchPreferences()]);
+
+  return (
+    <OnboardingPageContent
+      profile={profile as Parameters<typeof ProfileForm>[0]['initial']}
+      preferences={preferences}
+    />
+  );
+}
+
+function OnboardingPageContent({
+  profile,
+  preferences,
+}: {
+  profile: Parameters<typeof ProfileForm>[0]['initial'];
+  preferences: Awaited<ReturnType<typeof fetchPreferences>>;
+}) {
+  const t = useTranslations('Onboarding');
+
+  return (
+    <div className="mx-auto min-h-screen max-w-5xl px-6 sm:px-10">
+      <Masthead issueLabel="N. 03 — Inizio" />
+      <main className="py-12 sm:py-16">
+        <p className="editorial-eyebrow animate-fade-up">Capitolo III</p>
+        <h1 className="font-display text-display text-ink animate-fade-up mt-3 font-medium leading-[0.95] tracking-tight [animation-delay:120ms]">
+          {t('title')}
+          <span className="text-pomodoro">.</span>
+        </h1>
+        <p className="font-display text-ink-soft animate-fade-up mt-6 max-w-2xl text-xl italic leading-snug [animation-delay:240ms]">
+          {t('subtitle')}
+        </p>
+
+        <div className="rule animate-rule-in my-10 [animation-delay:360ms]" />
+
+        <OnboardingFlow initialProfile={profile} initialPreferences={preferences} />
+      </main>
+
+      <div className="rule-thick mt-16" />
+    </div>
+  );
+}