feat: add Playwright for end-to-end testing and create initial test suite

tests/e2e/home.spec.ts

@@ -0,0 +1,37 @@
+import { expect, test } from "@playwright/test"
+
+test.describe("home page", () => {
+  test("renders key sections without console errors", async ({ page }) => {
+    const consoleErrors: string[] = []
+    page.on("console", (message) => {
+      if (message.type() === "error") {
+        consoleErrors.push(message.text())
+      }
+    })
+
+    await page.goto("/")
+
+    await expect(page.getByRole("heading", { name: "My Snippets" })).toBeVisible()
+    await expect(
+      page.getByText("Save, organize, and share your code snippets", { exact: true })
+    ).toBeVisible()
+    await expect(page.locator("header")).toBeVisible()
+    await expect(page.locator("main")).toBeVisible()
+    await expect(page.locator("footer")).toBeVisible()
+
+    expect(consoleErrors).toEqual([])
+  })
+
+  test("stays within viewport on mobile (no horizontal overflow)", async ({ page }, testInfo) => {
+    test.skip(!testInfo.project.name.includes("mobile"), "mobile-only check")
+
+    await page.goto("/")
+
+    const overflow = await page.evaluate(() =>
+      Math.max(document.documentElement.scrollWidth - window.innerWidth, 0)
+    )
+
+    expect(overflow).toBeLessThanOrEqual(1)
+    await expect(page.getByRole("heading", { name: "My Snippets" })).toBeVisible()
+  })
+})