OTel: Custom Services empty state and Add creation entry point

* Add empty-state to the Custom Services page (icon, message, Add button)
* Add "Add custom service" page-menu shortcut
* Add empty ModeCreateCustomService (mode=create_otel_custom_service) and register it
* Extend E2E: page object for the creation page; test follows the Add flow

CMK-36035

Change-Id: Ibdfbc9041d9b8810b1a7af2ba4be8af2daf0ba48

Author: m3hransh

tests/system/gui/testlib/playwright/pom/setup/otel/add_custom_service.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# Copyright (C) 2026 Checkmk GmbH - License: GNU General Public License v2
+# This file is part of Checkmk (https://checkmk.com). It is subject to the terms and
+# conditions defined in the file COPYING, which is part of this source code package.
+import logging
+import re
+from typing import override
+
+from tests.system.gui.testlib.playwright.helpers import DropdownListNameToID
+from tests.system.gui.testlib.playwright.pom.page import CmkPage
+from tests.system.gui.testlib.playwright.pom.setup.otel.custom_services import CustomServices
+
+logger = logging.getLogger(__name__)
+
+
+class AddCustomService(CmkPage):
+    """Represent the page `Setup -> Telemetry -> Custom Services -> Add custom service`.
+
+    Empty for now (CMK-36035) — only the navigation into the creation flow exists.
+    """
+
+    page_title = "Add custom service"
+
+    @override
+    def navigate(self) -> None:
+        logger.info("Navigate to '%s' page", self.page_title)
+        custom_services_page = CustomServices(self.page)
+        self.click_and_wait_for_navigation(
+            custom_services_page.add_custom_service_button,
+            frame_url=re.compile("mode=create_otel_custom_service"),
+        )
+        self.validate_page()
+
+    @override
+    def validate_page(self) -> None:
+        logger.info("Validate that current page is '%s' page", self.page_title)
+        self.main_area.check_page_title(self.page_title)
+
+    @override
+    def _dropdown_list_name_to_id(self) -> DropdownListNameToID:
+        return DropdownListNameToID()

tests/system/gui/testlib/playwright/pom/setup/otel/custom_services.py

@@ -6,7 +6,7 @@
 import re
 from typing import override
 
-from playwright.sync_api import Locator
+from playwright.sync_api import expect, Locator
 
 from tests.system.gui.testlib.playwright.helpers import DropdownListNameToID
 from tests.system.gui.testlib.playwright.pom.page import CmkPage
@@ -34,6 +34,7 @@ def navigate(self) -> None:
     def validate_page(self) -> None:
         logger.info("Validate that current page is '%s' page", self.page_title)
         self.main_area.check_page_title(self.page_title)
+        expect(self.add_custom_service_button).to_be_visible()
 
     @override
     def _dropdown_list_name_to_id(self) -> DropdownListNameToID:
@@ -42,3 +43,7 @@ def _dropdown_list_name_to_id(self) -> DropdownListNameToID:
     @property
     def empty_state(self) -> Locator:
         return self.main_area.locator("div.no-config-bundles")
+
+    @property
+    def add_custom_service_button(self) -> Locator:
+        return self.main_area.get_suggestion("Add custom service")