FIELD: Field dialog, FIELD command and the ATTDEF field buttons

A Field dialog with the fields the application evaluates and the
reference format choices, FIELD placing a field as multi-line text, the
attribute definition dialogs' field buttons, field attachment on commit,
system variable / file size / regional date providers for field
evaluation, and the codec patch with the field authoring API.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/view/modal.rs

@@ -40,6 +40,7 @@ impl OpenCADStudio {
             Some(K::GeometricTolerance) => crate::t!("Geometric Tolerance").into_owned(),
             Some(K::AttDef) => crate::t!("Attribute Definition").into_owned(),
             Some(K::AttDefEdit) => crate::t!("Edit Attribute Definition").into_owned(),
+            Some(K::Field) => crate::t!("Field").into_owned(),
             Some(K::DraftingSettings) => crate::t!("Drafting Settings").into_owned(),
             Some(K::AutoConstrainSettings) => crate::t!("Constraint Settings").into_owned(),
             Some(K::LayerStateEditor) => crate::tr!("modal", "edit-layer-state"),
@@ -578,6 +579,10 @@ impl OpenCADStudio {
                 let state = self.attdef_dialog.as_ref()?;
                 sized_flow(ex, 720, 520, |flow| crate::ui::window::attdef_dialog::view(state, flow))
             }
+            super::super::ModalKind::Field => {
+                let state = self.field_dialog.as_ref()?;
+                sized_flow(ex, 760, 660, |flow| crate::ui::window::field_dialog::view(state, flow))
+            }
             super::super::ModalKind::AttDefEdit => {
                 let state = self.attdef_edit.as_ref()?;
                 sized_flow(ex, 460, 220, |flow| crate::ui::window::attdef_dialog::view_edit(state, flow))