Document Playwright MCP env vars and manual E2E steps

.env.example

@@ -21,3 +21,15 @@ LOG_LEVEL=info
 GOOGLE_CLIENT_ID=
 GOOGLE_CLIENT_SECRET=
 GOOGLE_REFRESH_TOKEN=
+
+# Playwright browser tools (MCP bridge). When PLAYWRIGHT_ENABLED=true the agent
+# gets ~60 browser_* tools (navigate, click, type, screenshot, run arbitrary
+# Playwright code, etc). The Docker image already ships Chromium; on a bare
+# host run `npx playwright install --with-deps chromium` first.
+PLAYWRIGHT_ENABLED=
+PLAYWRIGHT_HEADLESS=true
+# PLAYWRIGHT_BROWSER: chrome (default), firefox, webkit, msedge.
+PLAYWRIGHT_BROWSER=
+# PLAYWRIGHT_EXTRA_ARGS: shell-style extra flags for @playwright/mcp, e.g.
+#   PLAYWRIGHT_EXTRA_ARGS=--device "iPhone 15" --isolated
+PLAYWRIGHT_EXTRA_ARGS=