feat(api-docs): extract API docs viewer into standalone module

Move the Swagger UI viewer from core (pages/admin/api-docs/) into
modules/api-docs/ as a self-contained module. Create module manifest
with routes, permission, sidebar.admin_nav_item slot, asset group,
and authorization policy. Remove API docs ability from core
OperationsAuthorizationPolicy and UiCapabilityMap. Remove hardcoded
sidebar nav item — now contributed via module slot. Add
admin-automation group meta to sidebar template for module nav items.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/api-docs/i18n/default_de.json

@@ -0,0 +1,5 @@
+{
+  "API docs": "API-Dokumentation",
+  "API documentation": "API-Dokumentation",
+  "Can view API documentation": "Kann API-Dokumentation anzeigen"
+}