fix(signal): add missing accountUuid to Zod config schema

SignalAccountSchemaBase uses .strict() but was missing the
accountUuid field that is defined in SignalAccountConfig type
(types.signal.ts:10) and used at runtime for loop protection
(signal/monitor/event-handler.ts:456). This caused config
validation to reject channels.signal.accountUuid entries.

Add the field to the schema and a regression test.

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

@@ -184,4 +184,16 @@ describe("config schema regressions", () => {
 
     expect(res.ok).toBe(false);
   });
+
+  it("accepts signal accountUuid for loop protection", () => {
+    const res = validateConfigObject({
+      channels: {
+        signal: {
+          accountUuid: "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+        },
+      },
+    });
+
+    expect(res.ok).toBe(true);
+  });
 });

src/config/zod-schema.providers-core.ts

@@ -977,6 +977,7 @@ export const SignalAccountSchemaBase = z
     enabled: z.boolean().optional(),
     configWrites: z.boolean().optional(),
     account: z.string().optional(),
+    accountUuid: z.string().optional(),
     httpUrl: z.string().optional(),
     httpHost: z.string().optional(),
     httpPort: z.number().int().positive().optional(),