fix: language default, google OAuth cookie issue, add admin tier/usage controls

- ai-generate-dialog: useLocale() returns {locale,setLocale} object, not
  string — was stringifying whole object as default language value
- auth/server: add trustedOrigins so session cookie survives reverse-proxy
  deployments where BETTER_AUTH_URL differs from container's own view
- admin: add tier limit editor (/admin/tiers) and per-user usage reset
  button, both audit-logged

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

apps/web/app/admin/layout.tsx

@@ -3,13 +3,14 @@ import { headers } from "next/headers";
 import { auth } from "@/lib/auth/server";
 import { db, users, eq } from "@epicure/db";
 import Link from "next/link";
-import { Shield, Users, BookOpen, Settings, BarChart3, ClipboardList, HardDrive, Bot, ArrowLeft } from "lucide-react";
+import { Shield, Users, BookOpen, Settings, BarChart3, ClipboardList, HardDrive, Bot, ArrowLeft, Gauge } from "lucide-react";
 import { cn } from "@/lib/utils";
 
 const adminNav = [
   { href: "/admin", label: "Overview", icon: BarChart3 },
   { href: "/admin/users", label: "Users", icon: Users },
   { href: "/admin/recipes", label: "Recipes", icon: BookOpen },
+  { href: "/admin/tiers", label: "Tier Limits", icon: Gauge },
   { href: "/admin/audit-logs", label: "Audit Logs", icon: ClipboardList },
   { href: "/admin/storage", label: "Storage", icon: HardDrive },
   { href: "/admin/ai-config", label: "AI Config", icon: Bot },

apps/web/app/admin/tiers/page.tsx

@@ -0,0 +1,24 @@
+import type { Metadata } from "next";
+import { db, tierDefinitions } from "@epicure/db";
+import { TierLimitsForm } from "@/components/admin/tier-limits-form";
+
+export const metadata: Metadata = { title: "Tier Limits – Admin" };
+
+export default async function AdminTiersPage() {
+  const tiers = await db.select().from(tierDefinitions);
+
+  return (
+    <div className="space-y-8">
+      <div>
+        <h1 className="text-2xl font-bold tracking-tight">Tier Limits</h1>
+        <p className="text-muted-foreground text-sm mt-1">
+          Change monthly quotas per tier. Takes effect immediately for all users on that tier.
+        </p>
+      </div>
+
+      {tiers.map((tierDefinition) => (
+        <TierLimitsForm key={tierDefinition.tier} tierDefinition={tierDefinition} />
+      ))}
+    </div>
+  );
+}

apps/web/app/admin/users/[id]/page.tsx

@@ -6,6 +6,7 @@ import { Badge } from "@/components/ui/badge";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { Separator } from "@/components/ui/separator";
 import { UserEditor } from "@/components/admin/user-editor";
+import { ResetUsageButton } from "@/components/admin/reset-usage-button";
 import Link from "next/link";
 import { ArrowLeft } from "lucide-react";
 
@@ -118,6 +119,9 @@ export default async function AdminUserDetailPage({ params }: PageProps) {
               <span className="text-muted-foreground">Storage Used</span>
               <span className="font-medium">{usage?.storageUsedMb ?? 0} MB</span>
             </div>
+            <div className="pt-2">
+              <ResetUsageButton userId={user.id} />
+            </div>
           </CardContent>
         </Card>
       </div>

apps/web/app/api/v1/admin/tiers/[tier]/route.ts

@@ -0,0 +1,55 @@
+import { NextRequest, NextResponse } from "next/server";
+import { requireAdmin } from "@/lib/api-auth";
+import { db, tierDefinitions, auditLogs, eq } from "@epicure/db";
+import { randomUUID } from "crypto";
+
+interface RouteContext {
+  params: Promise<{ tier: string }>;
+}
+
+const NUMERIC_FIELDS = ["maxRecipes", "aiCallsPerMonth", "storageMb", "maxPublicRecipes"] as const;
+type NumericField = (typeof NUMERIC_FIELDS)[number];
+
+export async function PATCH(req: NextRequest, { params }: RouteContext) {
+  const { session, response } = await requireAdmin();
+  if (response) return response;
+
+  const { tier } = await params;
+  if (tier !== "free" && tier !== "pro") {
+    return NextResponse.json({ error: "Invalid tier" }, { status: 400 });
+  }
+
+  const body = (await req.json()) as Partial<Record<NumericField, number>>;
+  const updateData: Partial<Record<NumericField, number>> = {};
+
+  for (const field of NUMERIC_FIELDS) {
+    const value = body[field];
+    if (value === undefined) continue;
+    if (!Number.isInteger(value) || value < 0) {
+      return NextResponse.json({ error: `Invalid value for ${field}` }, { status: 400 });
+    }
+    updateData[field] = value;
+  }
+
+  const [updated] = await db
+    .update(tierDefinitions)
+    .set(updateData)
+    .where(eq(tierDefinitions.tier, tier))
+    .returning();
+
+  if (!updated) {
+    return NextResponse.json({ error: "Tier not found" }, { status: 404 });
+  }
+
+  await db.insert(auditLogs).values({
+    id: randomUUID(),
+    userId: session!.user.id,
+    action: "admin.tier.update",
+    targetType: "tier_definition",
+    targetId: tier,
+    metadata: JSON.stringify(updateData),
+    createdAt: new Date(),
+  });
+
+  return NextResponse.json({ tierDefinition: updated });
+}

apps/web/app/api/v1/admin/users/[id]/usage/route.ts

@@ -0,0 +1,39 @@
+import { NextRequest, NextResponse } from "next/server";
+import { requireAdmin } from "@/lib/api-auth";
+import { db, userUsage, auditLogs, eq, and } from "@epicure/db";
+import { randomUUID } from "crypto";
+
+interface RouteContext {
+  params: Promise<{ id: string }>;
+}
+
+function currentMonth() {
+  const now = new Date();
+  return `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, "0")}`;
+}
+
+export async function PATCH(req: NextRequest, { params }: RouteContext) {
+  const { session, response } = await requireAdmin();
+  if (response) return response;
+
+  const { id } = await params;
+  const month = currentMonth();
+
+  const [updated] = await db
+    .update(userUsage)
+    .set({ aiCallsUsed: 0, recipeCount: 0, storageUsedMb: 0 })
+    .where(and(eq(userUsage.userId, id), eq(userUsage.month, month)))
+    .returning();
+
+  await db.insert(auditLogs).values({
+    id: randomUUID(),
+    userId: session!.user.id,
+    action: "admin.user.reset_usage",
+    targetType: "user",
+    targetId: id,
+    metadata: JSON.stringify({ month }),
+    createdAt: new Date(),
+  });
+
+  return NextResponse.json({ usage: updated ?? { userId: id, month, aiCallsUsed: 0, recipeCount: 0, storageUsedMb: 0 } });
+}