Fix image rendering artifacts and improve show-images selector

- Image component returns correct number of lines (rows) for TUI accounting
- Empty lines rendered first, then cursor moves up and image is drawn
- This clears the space the image occupies before rendering
- Add spacer before inline images in tool output
- Create ShowImagesSelectorComponent with borders like other selectors
- Use showSelector pattern for /show-images command

packages/coding-agent/src/modes/interactive/components/tool-execution.ts

@@ -107,6 +107,7 @@ export class ToolExecutionComponent extends Container {
 			for (const img of imageBlocks) {
 				// Show inline image only if terminal supports it AND user setting allows it
 				if (caps.images && this.showImages && img.data && img.mimeType) {
+					this.addChild(new Spacer(1));
 					const imageComponent = new Image(
 						img.data,
 						img.mimeType,