feat: per-category email prefs, admin ops webhooks, per-user feature toggles (v0.61.0)

- Notification email preferences: every push category (follow, comment,
  reply, reaction, rating, mention, leftoverExpiring, shoppingList) now has
  an independent email toggle, plus a Weekly Digest toggle. Previously email
  sent unconditionally whenever the recipient had one; now gated the same
  way push already was. The weekly-digest cron route excludes opted-out
  users.

- Admin-only site-wide webhooks (Admin → Webhooks): new signups, support
  tickets, and reports filed can now fire an HMAC-signed HTTP webhook
  (Slack/Discord/ops alerting), independent of the existing per-user
  webhooks (which stay scoped to a user's own recipe/meal-plan/shopping-list
  events). Signing/delivery logic factored into lib/webhook-delivery.ts and
  shared by both dispatchers instead of duplicated.

- Settings → Features: users can hide Nutrition, Pantry, Meal Plan,
  Shopping Lists, Collections, or Messages from their own nav. Purely
  cosmetic — hidden pages stay reachable by direct link, nothing is
  access-restricted.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/messages/en.json

@@ -415,6 +415,7 @@
     "security": "Security",
     "aiModels": "AI & Models",
     "notifications": "Notifications",
+    "features": "Features",
     "nutrition": "Nutrition",
     "apiKeys": "API Keys",
     "webhooks": "Webhooks",
@@ -1399,7 +1400,9 @@
   "settingsForm": {
     "notificationCategories": {
       "title": "Notification categories",
-      "description": "Choose which push notifications you want to receive.",
+      "description": "Choose which notifications you want to receive, and whether by push, email, or both.",
+      "push": "Push",
+      "email": "Email",
       "follow": "New followers",
       "comment": "Comments on your recipes",
       "reply": "Replies to your comments",
@@ -1407,7 +1410,25 @@
       "rating": "Ratings on your recipes",
       "mention": "Mentions in comments",
       "leftoverExpiring": "Leftovers expiring soon",
-      "shoppingList": "Shared shopping list updates"
+      "shoppingList": "Shared shopping list updates",
+      "weeklyDigest": "Weekly digest",
+      "weeklyDigestDescription": "A weekly email summary of new followers, comments, and ratings, plus trending recipes."
+    },
+    "featureToggles": {
+      "title": "Features",
+      "description": "Hide features you don't use from your navigation. This only affects your own view — hidden pages stay reachable by direct link, nothing is deleted.",
+      "nutrition": "Nutrition",
+      "nutritionDescription": "Nutrition diary and goals.",
+      "pantry": "Pantry",
+      "pantryDescription": "Track what you have on hand.",
+      "mealPlan": "Meal Plan",
+      "mealPlanDescription": "Weekly meal planning.",
+      "shoppingLists": "Shopping Lists",
+      "shoppingListsDescription": "Shared shopping lists.",
+      "collections": "Collections",
+      "collectionsDescription": "Organize recipes into collections.",
+      "messages": "Messages",
+      "messagesDescription": "Direct messages with other cooks."
     },
     "profile": "Profile",
     "changePhoto": "Change photo",