fix(e2e): use --mode node for Vite in Playwright to skip cloudflare plugin

E2E tests use the Node backend (tsx watch server/entry-node.ts).
Without --mode node, Vite loads the cloudflare() plugin which starts
a Workers runtime that fails on missing env bindings.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

playwright.config.ts

@@ -20,7 +20,7 @@ export default defineConfig({
       reuseExistingServer: !process.env.CI,
     },
     {
-      command: 'vite',
+      command: 'vite --mode node',
       port: 5173,
       reuseExistingServer: !process.env.CI,
     },