Action registration missing createSchema — objectName field renders as plain text instead of object selector

[akarma-synetal]

Summary

When creating a new Action, the objectName field renders as a plain text input instead of a <Select> dropdown.

Root cause

In packages/app-shell/src/views/metadata-admin/anchors.ts, lines 350-375, Action has createFields: ['label', 'name', 'objectName', 'icon'] but provides no createSchema. Without a schema, SchemaForm renders every field as plain text. The objectName field never receives widget: 'ref:object'.

Note: the ActionSchema uses objectName (not object) as its object-binding field key.

Steps to reproduce

1. Navigate to Metadata → Action → Create new
2. Observe the Target Object field is a plain text input
3. Compare with Page → Create new — Object field is a proper dropdown

Expected behavior

objectName should render as a <Select> dropdown of existing objects.

Fix

Add a createSchema with widget: 'ref:object' on the objectName property.

Impact

Users must manually type the object name. Inconsistent with types that have createSchema.