Adds a new "basic" animation mode that uses React Flow's native animated
dashes — the entire stroke moves as dashes, with no solid line underneath.
Distinct from "snake" (moving dot) and "flow" (overlay on solid line).
- Frontend: new Basic button in EdgeModal, animMode mapping, passes
animated={true} to BaseEdge when mode is "basic"
- Backend: normalize_animated accepts "basic" as a valid value
- Tests: EdgeModal + canvas round-trip tests for basic mode
- canvasStore.onConnect: include animated in edge data object (was silently dropped)
- Backend schemas: normalize animated bool/int to string ('none'/'snake'/'flow') via field_validator
- ORM model: change animated column from Boolean to String
- DB migration: convert existing 0/1 boolean rows to 'none'/'snake' strings
Pouzor