Fix (UI): Connector polish and more

[ufuksarp]

Summary

What this PR adds

Makes connectors look and behave more like nodes (except their circle shape).

• Connector inputs and outputs use the same size and targets as nodes.
• Their colours and shapes match their connections.
• Dimming of invalid connections while dragging an edge matches node behaviour.
• Dragging from an input now applies the same dimming visual feedback correctly (fix for all nodes).

Under the hood

Shared nodeIOHandle styling for nodes and connectors. One resolver derives effective field types for chrome and edges: prefer upstream when it exists, otherwise infer through chains. Dragging from an input now uses the same validation as dragging from an output.

Feedback is very welcome. Let me know if you notice anything off or have ideas to make this more reliable, or look better.

Related Issues / Discussions

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QA Instructions

1. Add a connector then confirm its input and output feel like other nodes in size, shape, hitbox and colour.
2. Chain several connectors starting from both an input of a node and an output. Style should stay consistent through the whole chain for both directions.
3. Drag both from inputs and outputs and confirm the dim/highlight visual feedback works correctly for available connections.

Merge Plan

Standard merge

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable): connector topology unit tests updated/extended
• ❗Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)