feat: Phase 6 — require_active_service decorator + wizard install wiring

Email/calendar/files routes now return 404 when the service is not
installed, using a require_active_service decorator that checks
ServiceRegistry. Status endpoints are exempt so health checks always work.

SetupManager.complete_setup() now accepts a service_store_manager and
installs any wizard-selected services in a background daemon thread after
setup completes. Failures are logged but do not fail the wizard.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_email_endpoints.py

@@ -21,12 +21,21 @@ sys.path.insert(0, str(api_dir))
 
 from app import app
 
+# Sentinel value that make service_registry.get(...) return non-None (service installed)
+_INSTALLED = {'id': 'email', 'installed': True}
+
 
 class TestGetEmailUsers(unittest.TestCase):
 
     def setUp(self):
         app.config['TESTING'] = True
         self.client = app.test_client()
+        self._sr_patcher = patch('app.service_registry')
+        mock_sr = self._sr_patcher.start()
+        mock_sr.get.return_value = _INSTALLED
+
+    def tearDown(self):
+        self._sr_patcher.stop()
 
     @patch('app.email_manager')
     def test_get_users_returns_200_with_list(self, mock_em):
@@ -60,6 +69,12 @@ class TestCreateEmailUser(unittest.TestCase):
     def setUp(self):
         app.config['TESTING'] = True
         self.client = app.test_client()
+        self._sr_patcher = patch('app.service_registry')
+        mock_sr = self._sr_patcher.start()
+        mock_sr.get.return_value = _INSTALLED
+
+    def tearDown(self):
+        self._sr_patcher.stop()
 
     @patch('app.email_manager')
     def test_create_user_returns_200_on_success(self, mock_em):
@@ -131,6 +146,12 @@ class TestDeleteEmailUser(unittest.TestCase):
     def setUp(self):
         app.config['TESTING'] = True
         self.client = app.test_client()
+        self._sr_patcher = patch('app.service_registry')
+        mock_sr = self._sr_patcher.start()
+        mock_sr.get.return_value = _INSTALLED
+
+    def tearDown(self):
+        self._sr_patcher.stop()
 
     @patch('app.email_manager')
     def test_delete_user_returns_200_on_success(self, mock_em):
@@ -187,6 +208,12 @@ class TestEmailConnectivity(unittest.TestCase):
     def setUp(self):
         app.config['TESTING'] = True
         self.client = app.test_client()
+        self._sr_patcher = patch('app.service_registry')
+        mock_sr = self._sr_patcher.start()
+        mock_sr.get.return_value = _INSTALLED
+
+    def tearDown(self):
+        self._sr_patcher.stop()
 
     @patch('app.email_manager')
     def test_connectivity_returns_200_with_result(self, mock_em):