feature/prep reflex update

[cutoffthetop]

Changes

• prep reflex update:
  • avoid byte operators on Vars, use rx.cond instead
  • avoid Var.to_string(), use f-strings to render vars instead
  • avoid magical setters/getters on State, implement them explicitly
  • avoid calling event handlers from other event handlers, use private methods / direct assignments instead
  • avoid kwargs on event handlers, use positional Mapping argument instead
  • avoid getting granian warnings, set env var explicitly
  • avoid defaults for state model fields, making a swap to dataclasses easier
• fix some typing
• de-duplicate pagination component
• de-duplicate ingestion roundtrip tests