Fix missing spacer between assistant message and text editor

Initialize widgetContainer with default spacer during init() instead of
only when extension widgets change.

fixes #655

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -456,6 +456,7 @@ export class InteractiveMode {
 		this.ui.addChild(this.pendingMessagesContainer);
 		this.ui.addChild(this.statusContainer);
 		this.ui.addChild(this.widgetContainer);
+		this.renderWidgets(); // Initialize with default spacer
 		this.ui.addChild(this.editorContainer);
 		this.ui.addChild(this.footer);
 		this.ui.setFocus(this.editor);