Add kit selftest CI, Outline sync script, and close ops soak gaps

Fake-site Playwright suite catches BasePage/ApiClient/network regressions
before consumers pin a broken tag; Outline sync + docs for QA & Dev live page;
Pushgateway deploy soak confirmed separately on observability LXC.

package.json

@@ -42,6 +42,7 @@
     "typecheck": "tsc --noEmit",
     "test": "vitest run",
     "test:watch": "vitest",
+    "selftest": "playwright test -c selftest/playwright.config.ts",
     "lint": "tsc --noEmit",
     "prepublishOnly": "npm run build",
     "example:api": "tsx examples/api/health.example.ts"