Add Playwright E2E testing infrastructure

- New apps/e2e workspace with @playwright/test
- playwright.config.ts targeting Docker Compose stack (http://localhost:8080)
- navigation.spec.ts: smoke tests for all pages
- book.spec.ts: full booking wizard happy-path with API mocking
- clients.spec.ts: client list and detail panel tests
- CI job: spins up docker compose, installs Playwright chromium, runs tests
- Playwright report uploaded as artifact on failure
- README docs for running E2E tests locally

Closes #40

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/e2e/tests/navigation.spec.ts

@@ -0,0 +1,61 @@
+import { test, expect } from "@playwright/test";
+
+/**
+ * Navigation smoke tests — verifies that each page loads without errors.
+ * These tests mock all API calls so they can run without a live backend.
+ */
+
+test.beforeEach(async ({ page }) => {
+  // Intercept all API calls and return empty defaults so pages render
+  await page.route("/api/**", (route) => {
+    const url = route.request().url();
+    if (url.includes("/api/book/services")) {
+      return route.fulfill({ json: [] });
+    }
+    // Appointments, clients, services, staff, invoices, reports, etc.
+    return route.fulfill({ json: [] });
+  });
+});
+
+test("appointments page loads", async ({ page }) => {
+  await page.goto("/");
+  await expect(page.getByText("Groom Book")).toBeVisible();
+  // Calendar/appointments view renders
+  await expect(page.locator("nav")).toBeVisible();
+});
+
+test("clients page loads", async ({ page }) => {
+  await page.goto("/clients");
+  await expect(page.getByText("Groom Book")).toBeVisible();
+  await expect(page.getByRole("link", { name: "Clients" })).toBeVisible();
+});
+
+test("services page loads", async ({ page }) => {
+  await page.goto("/services");
+  await expect(page.getByText("Groom Book")).toBeVisible();
+  await expect(page.getByRole("link", { name: "Services" })).toBeVisible();
+});
+
+test("staff page loads", async ({ page }) => {
+  await page.goto("/staff");
+  await expect(page.getByText("Groom Book")).toBeVisible();
+  await expect(page.getByRole("link", { name: "Staff" })).toBeVisible();
+});
+
+test("invoices page loads", async ({ page }) => {
+  await page.goto("/invoices");
+  await expect(page.getByText("Groom Book")).toBeVisible();
+  await expect(page.getByRole("link", { name: "Invoices" })).toBeVisible();
+});
+
+test("reports page loads", async ({ page }) => {
+  await page.goto("/reports");
+  await expect(page.getByText("Groom Book")).toBeVisible();
+  await expect(page.getByRole("link", { name: "Reports" })).toBeVisible();
+});
+
+test("booking portal loads", async ({ page }) => {
+  await page.goto("/book");
+  await expect(page.getByText("Book an Appointment")).toBeVisible();
+  await expect(page.getByText("Choose a service")).toBeVisible();
+});