fix(discovery): add missing domain to wideArea Zod config schema

The wideArea schema uses .strict() but was missing the domain
field that is defined in WideAreaDiscoveryConfig type
(types.gateway.ts:21) and used across gateway, CLI, and
infrastructure code for unicast DNS-SD discovery.

Users setting discovery.wideArea.domain in their config get a
validation error.

Add the field to the schema and a regression test.

src/config/config.schema-regressions.test.ts

@@ -211,4 +211,17 @@ describe("config schema regressions", () => {
 
     expect(res.ok).toBe(true);
   });
+
+  it("accepts discovery.wideArea.domain for unicast DNS-SD", () => {
+    const res = validateConfigObject({
+      discovery: {
+        wideArea: {
+          enabled: true,
+          domain: "openclaw.internal",
+        },
+      },
+    });
+
+    expect(res.ok).toBe(true);
+  });
 });

src/config/zod-schema.ts

@@ -596,6 +596,7 @@ export const OpenClawSchema = z
         wideArea: z
           .object({
             enabled: z.boolean().optional(),
+            domain: z.string().optional(),
           })
           .strict()
           .optional(),