docs(e2e): describe how to run Playwright suite locally and read CI artifacts

Co-authored-by: cloudcode <cloudcode@users.noreply.github.com>

README.md

@@ -5,3 +5,59 @@
 ```bash
 npx swagger-typescript-api -p http://localhost:8008/swagger/doc.json -o ./src/types -n api.ts --no-client --union-enums
 ```
+
+## End-to-end tests
+
+Playwright suite lives in `tests/e2e/` and runs in CI via
+`.github/workflows/e2e.yml`. The workflow checks out the backend
+(`nezhahq/nezha` master), starts it on `127.0.0.1:8008`, then runs
+`npm run e2e` here.
+
+### Run locally
+
+First install browsers once:
+
+```bash
+npm run e2e:install
+```
+
+Then start the backend separately. The shape the CI workflow uses is:
+
+```bash
+# in a checkout of nezhahq/nezha
+mkdir -p cmd/dashboard/admin-dist cmd/dashboard/user-dist
+touch cmd/dashboard/admin-dist/.gitkeep cmd/dashboard/user-dist/.gitkeep
+go install github.com/swaggo/swag/cmd/swag@latest
+"$(go env GOPATH)/bin/swag" init --pd -d cmd/dashboard -g main.go -o cmd/dashboard/docs
+
+NZ_LISTENHOST=127.0.0.1 NZ_LISTENPORT=8008 \
+  NZ_JWTSECRETKEY=e2e-jwt-secret-key-min-32-chars-long-ok \
+  NZ_AGENTSECRETKEY=e2e-agent-secret-32-bytes-long-ok \
+  NZ_SITENAME=nezha-e2e GIN_MODE=release \
+  go run ./cmd/dashboard -c data/config.yaml -db data/sqlite.db
+```
+
+Then back in this repo:
+
+```bash
+npm run e2e            # Vite dev server starts automatically
+npm run e2e -- --ui    # interactive runner for debugging
+```
+
+### Reusing a running stack
+
+If you already have Vite (`npm run dev`) and the backend up:
+
+```bash
+E2E_SKIP_WEBSERVER=1 E2E_BASE_URL=http://localhost:5173 npm run e2e
+```
+
+Override credentials for a non-default admin account with `E2E_ADMIN_USER`
+and `E2E_ADMIN_PASS`.
+
+### Triaging a CI failure
+
+The workflow uploads two artifacts on failure:
+
+- `playwright-report` — HTML report; open `index.html` locally.
+- `dashboard-log` — full backend stdout/stderr for the test run.