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/app/(app)/support/page.tsx

@@ -5,14 +5,25 @@ import { db, supportTickets, eq, desc } from "@epicure/db";
 import { SupportManager } from "@/components/support/support-manager";
 import { getMessages } from "@/lib/i18n/server";
 import { getPublicUrl } from "@/lib/storage";
+import { FEATURE_DEFINITIONS } from "@/lib/feature-flags";
 
 export const metadata: Metadata = {};
 
-export default async function SupportPage() {
+export default async function SupportPage({
+  searchParams,
+}: {
+  searchParams: Promise<{ upgrade?: string }>;
+}) {
   const session = await auth.api.getSession({ headers: await headers() });
   if (!session) return null;
   const m = getMessages((session.user as { locale?: string }).locale);
 
+  const { upgrade } = await searchParams;
+  const upgradeFeature = FEATURE_DEFINITIONS.find((f) => f.key === upgrade);
+  const prefill = upgradeFeature
+    ? { type: "suggestion" as const, title: `Interested in upgrading for: ${upgradeFeature.label}` }
+    : undefined;
+
   const rows = await db.query.supportTickets.findMany({
     where: eq(supportTickets.userId, session.user.id),
     orderBy: desc(supportTickets.createdAt),
@@ -26,6 +37,7 @@ export default async function SupportPage() {
         <p className="text-muted-foreground text-sm mt-1">{m.support.subtitle}</p>
       </div>
       <SupportManager
+        prefill={prefill}
         initialTickets={rows.map((r) => ({
           id: r.id,
           type: r.type,