Remove contact identity fields from Stage 0 and widen Current stage

Drop the readonly First name, Last name, and Email fields from the
Check-in (organizing) section display. Add an optional fullWidth flag to
FieldConfig and set it on current_stage so it spans the full section grid.

types/form.ts

@@ -101,6 +101,12 @@ export interface FieldConfig {
    * FormDataPayload.options so the renderer can use real CRM-defined choices.
    */
   optionGroupId?: number;
+  /**
+   * Force this field to span the full width of the section grid (both
+   * columns), regardless of its type. Wide types (textarea, boolean,
+   * multiselect) already span by default.
+   */
+  fullWidth?: boolean;
 }
 
 /**