docs: 交付文档、维护指引与端到端回归

补齐 README、开发计划、维护交接与 E2E 用例，执行最终验收。

e2e/.gitignore

@@ -0,0 +1,13 @@
+node_modules/
+test-results/
+playwright-report/
+blob-report/
+.auth/
+.cache/
+.stack/
+.schemathesis/
+test-results-quarantine/
+playwright-report-quarantine/
+# Screenshot baselines are made on Linux in CI only.
+specs/**/*-snapshots/*-darwin.png
+specs/**/*-snapshots/*-win32.png