feat: přidání testů – Jest unit testy + Playwright E2E + CI pipeline

Server:
- Jest unit testy (88 testů): auth, utils, restaurants, service, voting, pizza
- in-memory storage mock pro izolaci testů
- oprava race condition při inicializaci Redis (storageReady promise)
- dev route dostupná i pro NODE_ENV=test
- getStatsMock deterministický (nahrazení Math.random)
- exporty interních helperů pro testovatelnost
- /api/health endpoint pro Playwright readiness check
- tsconfig vylučuje test soubory z produkčního buildu

E2E (e2e/):
- Playwright s Firefoxem + Chromiem
- testy: login, menu, výběr jídla, pizza day životní cyklus, QR/nastavení
- trusted-header auth bypass pro testy, video + trace při selhání

CI (Woodpecker):
- pipeline spouštěna na všech větvích a PR (nejen master)
- redis-stack-server service pro E2E – čistý Redis per větev automaticky
- kroky: unit testy, build, E2E testy (parallel kde možné)
- Docker build zůstává pouze pro master

Co-Authored-By: Claude Opus (extra usage) 4.7 <noreply@anthropic.com>

e2e/playwright.config.ts

@@ -0,0 +1,60 @@
+import { defineConfig, devices } from '@playwright/test';
+import path from 'path';
+
+// Use 127.0.0.1 explicitly — on Node.js 18+/Windows, `localhost` may resolve to ::1
+// (IPv6) while the HTTP server only binds to 0.0.0.0 (IPv4), causing the webServer
+// readiness poll to time out even though the server is listening.
+const BASE_URL = process.env.E2E_BASE_URL ?? 'http://127.0.0.1:3001';
+
+// Server env vars injected for local runs. In CI these are set at the step level.
+const serverEnv: Record<string, string> = {
+    NODE_ENV: 'test',
+    MOCK_DATA: 'true',
+    STORAGE: process.env.STORAGE ?? 'json',
+    JWT_SECRET: process.env.JWT_SECRET ?? 'e2e-test-secret-min-32-chars-aaaa',
+    HTTP_REMOTE_USER_ENABLED: 'true',
+    HTTP_REMOTE_USER_HEADER_NAME: 'remote-user',
+    HTTP_REMOTE_TRUSTED_IPS: process.env.HTTP_REMOTE_TRUSTED_IPS ?? '127.0.0.1,::1,::ffff:127.0.0.1',
+};
+if (process.env.REDIS_HOST) {
+    serverEnv.REDIS_HOST = process.env.REDIS_HOST;
+    serverEnv.REDIS_PORT = process.env.REDIS_PORT ?? '6379';
+}
+
+export default defineConfig({
+    testDir: './tests',
+    timeout: 30_000,
+    retries: process.env.CI ? 1 : 0,
+    workers: 1,
+    reporter: [['list'], ['html', { open: 'never' }]],
+    use: {
+        baseURL: BASE_URL,
+        // Default: every test authenticates as e2e-user via trusted header.
+        // Tests that need the real login form should override this in their own context.
+        extraHTTPHeaders: {
+            'remote-user': 'e2e-user',
+        },
+        trace: 'retain-on-failure',
+        video: 'retain-on-failure',
+    },
+    projects: [
+        { name: 'chromium', use: { ...devices['Desktop Chrome'] } },
+        { name: 'firefox', use: { ...devices['Desktop Firefox'] } },
+    ],
+    // Pre-built server must be started before tests. In CI the step does this
+    // explicitly. Locally: build types+server+client, cp -r client/dist server/public,
+    // then `cd e2e && yarn test` OR let webServer below do it if reuseExistingServer=true
+    // is set and the server is already running.
+    webServer: {
+        command: 'node dist/server/src/index.js',
+        cwd: path.resolve(__dirname, '../server'),
+        // Poll a dedicated health endpoint — polling '/' can stall in Express 5 when
+        // server/public/ doesn't exist in the working directory (no finalhandler match).
+        url: `http://127.0.0.1:3001/api/health`,
+        timeout: 15_000,
+        reuseExistingServer: !process.env.CI,
+        env: serverEnv,
+        stdout: 'pipe',
+        stderr: 'pipe',
+    },
+});