Buncha updates and improvements,
- adjust sub-namespace imports according to console warnings.
- iterate all detected screens in a loop and instead report which is the
primary and the current.
- type annotate all vars where non-obvious, particularly the`Qt` refs.
- use more compact optional value style with `|`-union
- fix `.flows` typing-only import since we need `MktPair` to be
immediately defined for use on a `msgspec.Struct` field.
- more "tree-like" warning msg in `.validate()` reporting.
Tyler Goodlet