fix(tui): handle split Shift+Enter in VS Code

packages/tui/test/input.test.ts

@@ -0,0 +1,30 @@
+import assert from "node:assert";
+import { describe, it } from "node:test";
+import { Input } from "../src/components/input.js";
+
+describe("Input component", () => {
+	it("treats split VS Code Shift+Enter as submit", () => {
+		const input = new Input();
+		let submitted: string | undefined;
+
+		input.setValue("hello");
+		input.onSubmit = (value) => {
+			submitted = value;
+		};
+
+		input.handleInput("\\");
+		input.handleInput("\r");
+
+		assert.strictEqual(submitted, "hello");
+		assert.strictEqual(input.getValue(), "hello");
+	});
+
+	it("inserts a literal backslash when not followed by Enter", () => {
+		const input = new Input();
+
+		input.handleInput("\\");
+		input.handleInput("x");
+
+		assert.strictEqual(input.getValue(), "\\x");
+	});
+});