Default File component imageSize to 100

[preshin]

Summary

Formio's File component defaults imageSize to '200', producing 200px-wide image previews that overflow narrow form layouts. This PR defaults it to 100 for newly added File components and for runtime forms whose JSON omits the property.

Why two parts

Naively wrapping FileComponent.schema() to inject imageSize: '100' is necessary but not sufficient. Formio's File editForm has a textfield bound to imageSize that is conditionally hidden until "Display as image(s)" is checked. That field inherits the global default clearOnHide: true, so as soon as the edit dialog renders, Formio strips data.imageSize (since the textfield is hidden) — wiping our seeded '100' before the user ever sees it. The preview <img> then renders with style="width:px" and the field shows only its hardcoded placeholder until the user retypes a number.

So the patch has two parts in src/index.js:

1. Schema wrap — sets the initial imageSize: '100' on new components / runtime defaults. User-provided imageSize in form JSON still wins via lodash _.merge.
2. EditForm walk — recursively walks the editForm structure and disables clearOnHide on the imageSize textfield so the seeded value persists through the initial hidden state.

Changes

• src/index.js — Patch 4 (matches the existing Patch 1–3 runtime-patch pattern).
• example/main.jsx — exposes the File component in the example builder so this patch has a regression target.
• package.json — 2.0.3 → 2.0.4.

Test plan

• npm run dev, drag a File component onto the example builder.
• Tick "Display as image(s)" → Image Size shows 100 as a real value.
• Drop an image → preview renders at 100px wide; <img> has style="width:100px".
• Expand "View JSON Schema Output" → component JSON has "imageSize": "100".
• Hand-edit a form's JSON to set imageSize: "300" → user value still wins.
• Console check: Formio.Components.components.file.schema() returns { ..., imageSize: "100" }.