feat: §5.2 finale — aderenza piano + export PDF

§5.2.5 Aderenza al piano alimentare
- MealSlot.consumed Boolean + consumedAt DateTime? (migration)
- POST /me/meal-plans/slots/:id/consumed (toggle, idempotente con body opzionale)
- @ketopath/shared/planner/adherence: computeAdherence() su slot dei giorni
  passati, free-meal contati come "rispettati"
- /plan: bottone ✓ in ogni SlotCard (oliva quando attivo) + 5° card nel
  summary settimanale "Aderenza: X% (n/m)"

§5.2.6 Export PDF per medico/nutrizionista
- pdfkit (Node, no headless Chrome) + @types/pdfkit
- GET /me/tracking/export.pdf: profilo, storico peso (30 entries),
  piano corrente con aderenza, footer con disclaimer medico
- Proxy Next.js /api/tracking-export per same-origin + cookie sessione
- /tracking: link "Esporta PDF per medico/nutrizionista" sotto subtitle

Schema migration: add_meal_slot_consumed.

81/81 unit test verdi. Lint, typecheck verdi.

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

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

@@ -73,6 +73,17 @@ function TrackingPageContent({
           {t('subtitle')}
         </p>
 
+        <p className="animate-fade-up mt-4 [animation-delay:300ms]">
+          <a
+            href="/api/tracking-export"
+            target="_blank"
+            rel="noopener noreferrer"
+            className="text-ink-soft decoration-pomodoro hover:text-ink font-mono text-[11px] uppercase tracking-widest underline decoration-[1.5px] underline-offset-[5px] transition-colors"
+          >
+            {t('exportPdf')} ↗
+          </a>
+        </p>
+
         <div className="rule animate-rule-in my-10 [animation-delay:360ms]" />
 
         <DailyCheckIn initial={todayCheckIn} />