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/lib/notifications.ts

@@ -3,7 +3,7 @@ import { randomUUID } from "crypto";
 import { sendPushNotification } from "./push";
 import { sendEmail, notificationEmailHtml } from "./email";
 import { getMessages, formatMessage } from "./i18n/server";
-import { isNotificationCategoryEnabled } from "./notification-prefs";
+import { isNotificationCategoryEnabled, isEmailCategoryEnabled } from "./notification-prefs";
 
 type NotificationType = "follow" | "comment" | "reply" | "reaction" | "rating" | "mention";
 
@@ -82,7 +82,7 @@ async function dispatchAlerts(opts: CreateNotificationOpts): Promise<void> {
     });
   }
 
-  if (recipient.email) {
+  if (recipient.email && (await isEmailCategoryEnabled(opts.userId, opts.type))) {
     const baseUrl = process.env["BETTER_AUTH_URL"] ?? "http://localhost:3000";
     void sendEmail({
       to: recipient.email,