sculpt: browse depot index files in '+' menu

This commit turns the '+' menu into a tool for the following tasks:

- Selecting and downloading of depot index files
- Browsing of the hierarchical depot index files
- Installation of packages found in the index files
- Interactive routing configuration of a selected package
- Deployment of configured component

repos/gems/run/sculpt/leitzentrale.config

@@ -140,6 +140,7 @@
 					</vfs>
 					<policy label="log" decoration="yes"/>
 					<policy label="runtime -> leitzentrale -> runtime_view" decoration="no" motion="20"/>
+					<policy label_prefix="gui -> popup" decoration="no" motion="20"/>
 					<policy label_prefix="gui" decoration="no"/>
 					<default-policy/>
 				</config>