feat(editor): type-checked connections + card-height fix + widget tests

Three changes:

1. Type-checked port connections. Drag from an output port
   only highlights compatible-type input ports as drop
   targets; incompatible drops are silently refused. Source
   of truth: ModuleSpec for declared types. When either side
   is unknown (no manifest, implicit YAML field) the check
   degrades to 'compatible with anything' so a missing
   manifest never blocks composition.

2. NodeGeometry.heightFor now adds a 2 px allowance for the
   1 px AnimatedContainer border on top + bottom of the
   card. Without this the last port-row's Column would
   overflow by 2 px under tight layout constraints (caught
   by the new widget tests; production canvas clipped it
   silently inside InteractiveViewer).

3. Width parameter on FlowNode now actually drives the
   outer SizedBox. The dynamic _stepWidth value from the
   canvas finally reaches the card border rather than being
   shadowed by NodeGeometry.width. Long labels
   (model_endpoint, source_language) no longer ellipsis-clip.

Tests: 8 new widget + geometry tests covering width growth,
two-column body layout, port-tooltip attachment,
row-alignment between input and output sides, and the
existing kindForStep classifier. All 20 editor tests pass.

Bumps fai_studio_flow_editor to 0.11.0.

Signed-off-by: flemming-it <sf@flemming.it>

pubspec.yaml

@@ -1,6 +1,6 @@
 name: fai_studio_flow_editor
 description: Swappable inline YAML editor for F∆I Studio flows.
-version: 0.10.3
+version: 0.11.0
 publish_to: 'none'
 repository: https://git.flemming.ai/fai/studio-flow-editor