Fix load_object color refresh on MODELS change

[tracygardner]

Motivation

• Selecting a different model in the load_object block did not immediately update the connected COLOR shadow/input to the default from objectColours, breaking the expected live-update behavior when swapping items.

Description

• Added a specific onChange check in blocks/models.js to call updateColorField() when the MODELS field changes on the load_object block so the connected COLOR value is refreshed from the config immediately.

Testing

• Ran the production build with npm run build, which completed successfully (Vite emitted non-blocking warnings about chunking/externalized modules but the build finished).

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Codex Task