feat(admin): pages Marketing et Statistiques (sans envoi)

Ajoute deux entrées au menu d’administration. Les campagnes s’affichent dans un tableau vide honnête. Les statistiques disent clairement qu’aucune mesure n’est encore branchée, sans afficher de zéro trompeur.

memento-note/locales/en.json

@@ -1598,7 +1598,42 @@
       "chat": "AI Chat",
       "lab": "The Lab (Ideas)",
       "agents": "Agents",
-      "settings": "Settings"
+      "settings": "Settings",
+      "marketing": "Marketing",
+      "stats": "Statistics"
+    },
+    "marketing": {
+      "title": "Marketing",
+      "description": "Prepare campaigns, choose who receives them, and attach an offer. Sending is not enabled yet.",
+      "emptyTitle": "No campaigns yet",
+      "emptyBody": "When campaigns exist, they will appear in this table with their audience, offer, and status. Nothing is sent from this page.",
+      "createCampaign": "Create a campaign",
+      "createDisabledHint": "Campaign sending is not enabled in this version.",
+      "columns": {
+            "name": "Internal name",
+            "goal": "Purpose",
+            "audience": "Audience",
+            "language": "Language",
+            "offer": "Offer",
+            "status": "Status",
+            "scheduledAt": "Scheduled date",
+            "accepted": "Accepted by the mail service",
+            "delivered": "Delivered",
+            "paidConversions": "Paid conversions"
+      }
+    },
+    "stats": {
+      "title": "Statistics",
+      "description": "Revenue, subscriptions, product activity, and campaign results. Figures appear only from a reliable source.",
+      "unavailable": "Not available yet",
+      "unavailableBody": "This section is not connected to a measurement source. It does not show zero, because zero would mean “nothing happened”.",
+      "lastSyncUnknown": "Last update: unknown",
+      "sectionRevenue": "Revenue",
+      "sectionSubscriptions": "Subscriptions",
+      "sectionUsage": "Usage",
+      "sectionCampaigns": "Campaigns",
+      "periodLabel": "Period",
+      "timezoneNote": "Dates follow the administrator’s time zone once measurements exist."
     },
     "metrics": {
       "vsLastPeriod": "vs last period"