feat: integrate Better Auth and enhance authentication flow

- Added Better Auth integration to the web application, allowing for dual login support with both custom and Better Auth systems.
- Updated authentication client configuration to dynamically set the base URL based on the environment.
- Enhanced chat components to utilize user authentication status, improving user experience and security.
- Refactored various components to support Better Auth, including error handling and user identity management.
- Improved notification handling and user feedback mechanisms during authentication processes.

apps/web/src/lib/auth.ts

@@ -1,7 +1,21 @@
-import { createAuthClient } from "better-auth/client";
+/**
+ * Cliente Better Auth para frontend SvelteKit
+ * 
+ * Configurado para trabalhar com Convex via plugin convexClient.
+ * Este cliente será usado para autenticação quando Better Auth estiver ativo.
+ */
+import { createAuthClient } from "better-auth/svelte";
 import { convexClient } from "@convex-dev/better-auth/client/plugins";
 
 export const authClient = createAuthClient({
-  baseURL: "http://localhost:5173",
-  plugins: [convexClient()],
+  // Base URL da API Better Auth (mesma do app)
+  baseURL: typeof window !== "undefined" 
+    ? window.location.origin  // Usar origem atual em produção
+    : "http://localhost:5173", // Fallback para desenvolvimento
+  plugins: [
+    // Plugin Convex integra Better Auth com Convex backend
+    convexClient({
+      convexUrl: import.meta.env.PUBLIC_CONVEX_URL || "",
+    }),
+  ],
 });