feat: per-tier feature toggles for recipe variations/pairings (v0.50.0)

Admins can now disable specific AI features per tier from Admin > Tier
Limits — new feature_flags table (feature x tier -> enabled, defaulting
to true so adding a new gated feature never needs a backfill).

Covers recipe variations, drink pairing, and meal pairing to start.
When disabled for a user's tier, the button stays visible (with a small
lock badge) but opens an upgrade dialog instead of running; the API
route rejects the call server-side either way (requireFeatureEnabled,
re-reads tier from the DB rather than trusting the session's cache,
same rationale as checkAndIncrementTierLimit).

The upgrade dialog is informational only — no Stripe checkout exists
yet (STRIPE_PLAN.md is still just a plan) — its CTA links to /support
prefilled as an upgrade-interest suggestion.

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

apps/web/components/recipe/drink-pairing-button.tsx

@@ -2,7 +2,7 @@
 
 import { useState } from "react";
 import { useTranslations } from "next-intl";
-import { Wine, Sparkles, Loader2, Coffee, Beer, GlassWater, Leaf } from "lucide-react";
+import { Wine, Sparkles, Loader2, Coffee, Beer, GlassWater, Leaf, Lock } from "lucide-react";
 import { FakeProgressBar } from "@/components/ui/fake-progress-bar";
 import { toast } from "sonner";
 import { Button } from "@/components/ui/button";
@@ -16,6 +16,7 @@ import {
 } from "@/components/ui/dialog";
 import { Badge } from "@/components/ui/badge";
 import { Separator } from "@/components/ui/separator";
+import { UpgradeDialog } from "@/components/premium/upgrade-dialog";
 
 type Drink = {
   name: string;
@@ -45,9 +46,10 @@ const TYPE_LABEL_KEY: Record<Drink["type"], string> = {
   hot: "drinksTypeHot",
 };
 
-export function DrinkPairingButton({ recipeId }: { recipeId: string }) {
+export function DrinkPairingButton({ recipeId, locked = false }: { recipeId: string; locked?: boolean }) {
   const t = useTranslations("recipe");
   const [open, setOpen] = useState(false);
+  const [upgradeOpen, setUpgradeOpen] = useState(false);
   const [loading, setLoading] = useState(false);
   const [drinks, setDrinks] = useState<Drink[]>([]);
 
@@ -72,6 +74,10 @@ export function DrinkPairingButton({ recipeId }: { recipeId: string }) {
   }
 
   function handleOpen() {
+    if (locked) {
+      setUpgradeOpen(true);
+      return;
+    }
     setOpen(true);
     if (drinks.length === 0) suggest();
   }
@@ -81,14 +87,22 @@ export function DrinkPairingButton({ recipeId }: { recipeId: string }) {
       <TooltipProvider>
         <Tooltip>
           <TooltipTrigger render={
-            <Button variant="ghost" size="icon" onClick={handleOpen} aria-label={t("drinksTooltip")}>
+            <Button variant="ghost" size="icon" onClick={handleOpen} aria-label={t("drinksTooltip")} className="relative">
               <Wine className="h-4 w-4" />
+              {locked && <Lock className="h-2.5 w-2.5 absolute bottom-1 right-1 text-muted-foreground" />}
             </Button>
           } />
           <TooltipContent>{t("drinksTooltip")}</TooltipContent>
         </Tooltip>
       </TooltipProvider>
 
+      <UpgradeDialog
+        open={upgradeOpen}
+        onOpenChange={setUpgradeOpen}
+        featureKey="drink_pairing"
+        featureLabel="Drink pairing"
+      />
+
       <Dialog open={open} onOpenChange={setOpen}>
         <DialogContent className="max-w-2xl max-h-[80vh] overflow-y-auto">
           <DialogHeader>