Model upload missing from WidgetSelect

## Recommendation

### 🔧 FINISH: Add model upload support to WidgetSelect

The upload/browse path handles image, video, and audio but not model types (checkpoints, VAE, LoRAs).

## What Was Found

- `src/renderer/extensions/vueNodes/widgets/components/WidgetSelect.vue:87` — `// TODO: add support for models (checkpoints, VAE, LoRAs, etc.)`

## Context

Widget select supports upload for media types but model widgets lack this capability.

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**Category:** Half-Implemented | **Confidence:** HIGH | **Tools:** Semantic analysis
_Filed by audit-code skill_

Part of #11022

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-11043-Model-upload-missing-from-WidgetSelect-33e6d73d3650818d9cb3f18074d97ac5) by [Unito](https://www.unito.io)