One test per AC of specs/fronius-sunspec.md, named test_AC_<n>_<what>.
Definition criteria (value ranges, thing classes, defaults) are checked by
re-reading integrationpluginsunspec.json. Behaviour criteria run either on
a model 124 register dump fed to the real libnymea-sunspec model, or on the
pure logic units the plugin is about to grow.
All red at this point: sunspecstoragelogic and froniusrules do not exist
yet, so the suite does not compile. That is the expected starting state.
