feat: granular per-category push notification settings

New Settings → Notifications section with a toggle per category (follow,
comment, reply, reaction, rating, mention, leftover-expiring, shared
shopping list) — previously it was all-or-nothing (browser permission only).

userNotificationPrefs (one row per user, defaults all-on so existing users
see no behavior change until they opt out of something). Gated the push
send in the three places that dispatch one: lib/notifications.ts (the 6
in-app notification types), the leftover-expiry cron, and shopping-list-notify
— in-app notification-center entries and email are unaffected, this only
gates the push itself, matching the literal ask.

Verified locally: GET/PUT round-trips correctly, disabling a category
and confirming the settings page renders all 8 toggles.

apps/web/messages/fr.json

@@ -1056,6 +1056,18 @@
     }
   },
   "settingsForm": {
+    "notificationCategories": {
+      "title": "Catégories de notifications",
+      "description": "Choisissez les notifications push que vous souhaitez recevoir.",
+      "follow": "Nouveaux abonnés",
+      "comment": "Commentaires sur vos recettes",
+      "reply": "Réponses à vos commentaires",
+      "reaction": "Réactions à vos commentaires",
+      "rating": "Notes sur vos recettes",
+      "mention": "Mentions dans les commentaires",
+      "leftoverExpiring": "Restes bientôt périmés",
+      "shoppingList": "Mises à jour des listes de courses partagées"
+    },
     "profile": "Profil",
     "changePhoto": "Changer la photo",
     "removePhoto": "Supprimer la photo",