test: add Playwright e2e smoke suite for punimtag dev

Add an e2e/ Playwright harness (via @levkin/playkit) that smoke-tests
the public DEV host: login page loads, sign-out never redirects to a
LAN host, FastAPI /health responds, and forgot-password mail lands in
Mailtrap with a public reset link (Kolby #56/#57 regressions).

Wire it into Gitea Actions as a new `e2e` job (self-hosted runner,
Chromium via Playwright), gated behind the existing skip-ci-check.
Add npm root scripts (install:e2e, test:e2e) and gitignore e2e build
artifacts (node_modules, reports, .env).

e2e/playwright.config.ts

@@ -0,0 +1,27 @@
+import { defineConfig, devices } from '@playwright/test';
+
+const baseURL =
+  process.env.PLAYKIT_BASE_URL ||
+  process.env.BASE_URL ||
+  'https://punimtagdev.levkin.ca';
+
+export default defineConfig({
+  testDir: './tests',
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 1 : 0,
+  workers: process.env.CI ? 2 : undefined,
+  reporter: process.env.CI
+    ? [['list'], ['html', { open: 'never' }], ['junit', { outputFile: 'test-results/junit.xml' }]]
+    : [['list'], ['html', { open: 'on-failure' }]],
+  timeout: 60_000,
+  expect: { timeout: 15_000 },
+  use: {
+    baseURL,
+    trace: 'retain-on-failure',
+    screenshot: 'only-on-failure',
+    video: 'retain-on-failure',
+    ...devices['Desktop Chrome'],
+  },
+  projects: [{ name: 'chromium', use: { ...devices['Desktop Chrome'] } }],
+});