Implement stub indexes for store and components

Not implementing these indexes will eventually cause a performance issue.

In case we could not implement these indexes, we have to describe Catberry syntax for templates.

The issue does not name any files, tests, or entry points. Start by locating the IntelliJ plugin code for store and component indexes, then determine whether those indexes can be implemented; if not, identify where Catberry template syntax documentation belongs. Done means the indexes work or the required syntax is documented, but the issue does not define acceptance details.

Written by the indexing model from the issue text.