chore: changeset for object-form screen wizard

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: os-zhuang

.changeset/object-form-screen-wizard.md

@@ -0,0 +1,20 @@
+---
+"@objectstack/spec": minor
+"@objectstack/service-automation": minor
+---
+
+feat(automation): object-form screen-flow steps
+
+A `screen` node that declares `config.objectName` now renders the named object's
+FULL create/edit form (including inline master-detail child grids) instead of a
+flat field list. The node emits an `object-form` `ScreenSpec`
+(`kind`/`objectName`/`mode`/`recordId`/`defaults`/`idVariable`); the client
+renders the real ObjectForm, persists the record (and its children, atomically),
+and resumes the run with the saved id bound to `idVariable` so a later step can
+reference it — e.g. a lead-conversion wizard: a full Customer step, then a full
+Opportunity-with-line-items step.
+
+- **spec**: `ScreenSpec` gains `kind`/`objectName`/`mode`/`recordId`/`defaults`/`idVariable`.
+- **service-automation**: the `screen` executor emits object-form specs and now
+  interpolates `title`/`description`/field `defaultValue`/object-form `defaults`
+  against live flow variables (the engine does not pre-interpolate node config).