feat: manage system appearance defaults

src/govoplan_admin/backend/manifest.py

@@ -75,7 +75,7 @@ manifest = ModuleManifest(
             id="admin.workspace",
             title="Use the administration workspace",
             summary="The administration workspace shows only the sections supplied by enabled modules and allowed by the current account's permissions.",
-            body="System and tenant administration share one workspace. Available sections can include settings, configuration changes and packages, governance templates, groups, and module lifecycle controls. A missing section normally means that its owning module is disabled or the current account lacks the required authority.",
+            body="System and tenant administration share one workspace. Available sections can include settings, configuration changes and packages, governance templates, groups, and module lifecycle controls. A missing section normally means that its owning module is disabled or the current account lacks the required authority. System appearance settings select a validated palette default. Changing the separate palette lock additionally requires policy-write authority; a system lock suppresses tenant and personal palette choices, while an unlocked default remains inheritable and overridable.",
             documentation_types=("admin", "user"),
             audience=("tenant_admin", "system_admin", "operator"),
             metadata={