feat: admin Ingredients CRUD UI; fix "page not found" after deleting shopping list/recipe/collection (v0.85.0)

Admin > Ingredients lets admins add/edit/delete canonical ingredients and their aliases (e.g. "sel"/"sel fin"/"table salt") without touching code — previously only settable by hand in packages/db/src/seed.ts. Deleting just unlinks referencing pantry items/recipe ingredients (onDelete: set null), nothing else changes.

Fixed: deleting a shopping list, recipe, or collection from its own detail page used router.push to navigate away, leaving the deleted resource's URL in browser history — one back-button press landed on a real "Page not found" screen. All three now use router.replace so the dead URL never sits in history.

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

apps/web/app/admin/layout.tsx

@@ -1,5 +1,5 @@
 import Link from "next/link";
-import { Shield, Users, BookOpen, Settings, BarChart3, ClipboardList, HardDrive, Bot, ArrowLeft, Gauge, Mail, Flag, History, LifeBuoy, TrendingUp, Webhook, CreditCard } from "lucide-react";
+import { Shield, Users, BookOpen, Settings, BarChart3, ClipboardList, HardDrive, Bot, ArrowLeft, Gauge, Mail, Flag, History, LifeBuoy, TrendingUp, Webhook, CreditCard, Tag } from "lucide-react";
 import { cn } from "@/lib/utils";
 import { getStaffRole } from "@/lib/require-admin-page";
 import { redirect } from "next/navigation";
@@ -16,6 +16,7 @@ const adminNav = [
   { href: "/admin/reports", label: "Reports", icon: Flag, adminOnly: false },
   { href: "/admin/support", label: "Support", icon: LifeBuoy, adminOnly: true },
   { href: "/admin/tiers", label: "Tier Limits", icon: Gauge, adminOnly: true },
+  { href: "/admin/ingredients", label: "Ingredients", icon: Tag, adminOnly: true },
   { href: "/admin/billing", label: "Billing", icon: CreditCard, adminOnly: true },
   { href: "/admin/webhooks", label: "Webhooks", icon: Webhook, adminOnly: true },
   { href: "/admin/audit-logs", label: "Audit Logs", icon: ClipboardList, adminOnly: true },