fix: Bug - Login screen shows up on unreachable signal servers

Skip authorize login navigation when a signal server endpoint is offline or
unreachable; gate connection and credential flows on online status only.

Co-authored-by: Cursor <cursoragent@cursor.com>

toju-app/src/app/domains/server-directory/domain/logic/server-endpoint-connectivity.rules.spec.ts

@@ -0,0 +1,17 @@
+import {
+  describe,
+  expect,
+  it
+} from 'vitest';
+import { isEndpointOnlineForConnection } from './server-endpoint-connectivity.rules';
+
+describe('server-endpoint-connectivity rules', () => {
+  it('treats only online endpoints as reachable for connection', () => {
+    expect(isEndpointOnlineForConnection('online')).toBe(true);
+    expect(isEndpointOnlineForConnection('offline')).toBe(false);
+    expect(isEndpointOnlineForConnection('checking')).toBe(false);
+    expect(isEndpointOnlineForConnection('unknown')).toBe(false);
+    expect(isEndpointOnlineForConnection('incompatible')).toBe(false);
+    expect(isEndpointOnlineForConnection(undefined)).toBe(false);
+  });
+});