feat(custom-widgets): complete Custom JSX v2 (#6390)

apps/nextjs/src/env.ts

@@ -1,3 +1,5 @@
+import { z } from "zod/v4";
+
 import { createBooleanSchema, createEnv } from "@homarr/core/infrastructure/env";
 
 export const env = createEnv({
@@ -5,6 +7,7 @@ export const env = createEnv({
     UNSAFE_ENABLE_MOCK_INTEGRATION: createBooleanSchema(false),
     DEMO_MODE: createBooleanSchema(false),
     DEMO_READ_ONLY: createBooleanSchema(true),
+    WORKSHOP_API_URL: z.string().url().optional(),
   },
   experimental__runtimeEnv: process.env,
 });