chore(ts): use source import extensions

packages/tui/test/overlay-short-content.test.ts

@@ -4,7 +4,12 @@ import { type Component, TUI } from "../src/tui.js";
 import { VirtualTerminal } from "./virtual-terminal.js";
 
 class SimpleContent implements Component {
-	constructor(private lines: string[]) {}
+	private lines: string[];
+
+	constructor(lines: string[]) {
+		this.lines = lines;
+	}
+
 	render(): string[] {
 		return this.lines;
 	}