Add workflow templates version tracking to system_stats (#9089)

Adds installed and required workflow templates version information to the
/system_stats endpoint, allowing the frontend to detect and notify users
when their templates package is outdated.

- Add get_installed_templates_version() and get_required_templates_version()
  methods to FrontendManager
- Include templates version info in system_stats response
- Add comprehensive unit tests for the new functionality

tests-unit/app_test/frontend_manager_test.py

@@ -205,3 +205,74 @@ numpy"""
 
     # Assert
     assert version is None
+
+
+def test_get_templates_version():
+    # Arrange
+    expected_version = "0.1.41"
+    mock_requirements_content = """torch
+torchsde
+comfyui-frontend-package==1.25.0
+comfyui-workflow-templates==0.1.41
+other-package==1.0.0
+numpy"""
+
+    # Act
+    with patch("builtins.open", mock_open(read_data=mock_requirements_content)):
+        version = FrontendManager.get_required_templates_version()
+
+    # Assert
+    assert version == expected_version
+
+
+def test_get_templates_version_not_found():
+    # Arrange
+    mock_requirements_content = """torch
+torchsde
+comfyui-frontend-package==1.25.0
+other-package==1.0.0
+numpy"""
+
+    # Act
+    with patch("builtins.open", mock_open(read_data=mock_requirements_content)):
+        version = FrontendManager.get_required_templates_version()
+
+    # Assert
+    assert version is None
+
+
+def test_get_templates_version_invalid_semver():
+    # Arrange
+    mock_requirements_content = """torch
+torchsde
+comfyui-workflow-templates==1.0.0.beta
+other-package==1.0.0
+numpy"""
+
+    # Act
+    with patch("builtins.open", mock_open(read_data=mock_requirements_content)):
+        version = FrontendManager.get_required_templates_version()
+
+    # Assert
+    assert version is None
+
+
+def test_get_installed_templates_version():
+    # Arrange
+    expected_version = "0.1.40"
+
+    # Act
+    with patch("app.frontend_management.version", return_value=expected_version):
+        version = FrontendManager.get_installed_templates_version()
+
+    # Assert
+    assert version == expected_version
+
+
+def test_get_installed_templates_version_not_installed():
+    # Act
+    with patch("app.frontend_management.version", side_effect=Exception("Package not found")):
+        version = FrontendManager.get_installed_templates_version()
+
+    # Assert
+    assert version is None