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]/plan/page.tsx

@@ -21,7 +21,7 @@ export default async function PlanPage({ params: { locale } }: { params: { local
     select: { disclaimerAcceptedAt: true, profile: { select: { id: true } } },
   });
   if (!user?.disclaimerAcceptedAt) redirect('/welcome');
-  if (!user.profile) redirect('/profile');
+  if (!user.profile) redirect('/onboarding');
 
   const plan = await fetchCurrentPlan();