feat: núcleo de tickets com Convex (CRUD, play, comentários com anexos) + auth placeholder; docs em AGENTS.md; toasts e updates otimistas; mapeadores Zod; refinos PT-BR e layout do painel de detalhes

web/src/lib/auth-client.tsx

@@ -0,0 +1,50 @@
+"use client";
+
+import React, { createContext, useContext, useEffect, useMemo, useState } from "react";
+import { useMutation } from "convex/react";
+
+// Lazy import to avoid build errors before convex is generated
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import { api } from "../../convex/_generated/api";
+
+export type DemoUser = { name: string; email: string; avatarUrl?: string } | null;
+
+type AuthContextValue = {
+  demoUser: DemoUser;
+  userId: string | null;
+  setDemoUser: (u: DemoUser) => void;
+};
+
+const AuthContext = createContext<AuthContextValue>({ demoUser: null, userId: null, setDemoUser: () => {} });
+
+export function useAuth() {
+  return useContext(AuthContext);
+}
+
+export function AuthProvider({ demoUser, tenantId, children }: { demoUser: DemoUser; tenantId: string; children: React.ReactNode }) {
+  const [localDemoUser, setLocalDemoUser] = useState<DemoUser>(demoUser);
+  const [userId, setUserId] = useState<string | null>(null);
+  const ensureUser = useMutation(api.users.ensureUser);
+
+  useEffect(() => {
+    async function run() {
+      if (!process.env.NEXT_PUBLIC_CONVEX_URL) return; // allow dev without backend
+      if (!localDemoUser) return;
+      try {
+        const user = await ensureUser({ tenantId, name: localDemoUser.name, email: localDemoUser.email, avatarUrl: localDemoUser.avatarUrl });
+        // Convex returns a full document
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        setUserId((user as any)?._id ?? null);
+      } catch (e) {
+        console.error("Failed to ensure user:", e);
+      }
+    }
+    run();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [localDemoUser?.email, tenantId]);
+
+  const value = useMemo(() => ({ demoUser: localDemoUser, setDemoUser: setLocalDemoUser, userId }), [localDemoUser, userId]);
+  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
+}
+