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/authentication/domain/logic/signal-server-authorize.rules.spec.ts

@@ -0,0 +1,44 @@
+import {
+  describe,
+  expect,
+  it
+} from 'vitest';
+import { shouldNavigateToAuthorizeSignalServer } from './signal-server-authorize.rules';
+
+describe('signal-server-authorize rules', () => {
+  it('does not navigate to authorize when the signal server is offline', () => {
+    expect(shouldNavigateToAuthorizeSignalServer('offline', {
+      kind: 'skipped',
+      reason: 'no-provision-secret'
+    })).toBe(false);
+
+    expect(shouldNavigateToAuthorizeSignalServer('offline', {
+      kind: 'collision',
+      error: new Error('collision') as never
+    })).toBe(false);
+  });
+
+  it('navigates to authorize on online servers that need manual sign-in', () => {
+    expect(shouldNavigateToAuthorizeSignalServer('online', {
+      kind: 'skipped',
+      reason: 'no-provision-secret'
+    })).toBe(true);
+
+    expect(shouldNavigateToAuthorizeSignalServer('online', {
+      kind: 'collision',
+      error: new Error('collision') as never
+    })).toBe(true);
+  });
+
+  it('does not navigate for unknown endpoint status or non-authorize provision outcomes', () => {
+    expect(shouldNavigateToAuthorizeSignalServer('unknown', {
+      kind: 'skipped',
+      reason: 'no-provision-secret'
+    })).toBe(false);
+
+    expect(shouldNavigateToAuthorizeSignalServer('online', {
+      kind: 'skipped',
+      reason: 'no-home-user'
+    })).toBe(false);
+  });
+});

toju-app/src/app/domains/authentication/domain/logic/signal-server-authorize.rules.ts

@@ -0,0 +1,18 @@
+import type { EnsureProvisionedResult } from '../../application/services/signal-server-auth.service';
+import type { ServerEndpointStatus } from '../../../server-directory/domain/models/server-directory.model';
+import { isEndpointOnlineForConnection } from '../../../server-directory/domain/logic/server-endpoint-connectivity.rules';
+
+export function shouldNavigateToAuthorizeSignalServer(
+  endpointStatus: ServerEndpointStatus | undefined | null,
+  provisionResult: EnsureProvisionedResult
+): boolean {
+  if (!isEndpointOnlineForConnection(endpointStatus)) {
+    return false;
+  }
+
+  if (provisionResult.kind === 'collision') {
+    return true;
+  }
+
+  return provisionResult.kind === 'skipped' && provisionResult.reason === 'no-provision-secret';
+}