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>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.60.0",
+  "version": "0.61.0",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",