feat: add CI, Docker, auth, typed API client, shiki code blocks, e2e tests

- CI: GitHub Actions (bun 1.3.14, lint/typecheck/test/build/format gates)
- Docker: multi-stage standalone build + .dockerignore (next.config output=standalone)
- Auth: better-auth server (memory adapter, drizzle-swap-ready) + react client
  + /api/auth/[...all] route handler
- API: /api/health + /api/openapi routes, openapi-typescript codegen to
  types/api.ts, typed openapi-fetch client (lib/api, lib/http)
- Shiki: server-side CodeBlock component (escaped HTML)
- E2E: playwright home + health specs on dedicated :3100 (chromium 1243
  installed from GCS after CDN timeout)
- Dev: allow 127.0.0.1/localhost dev origins (HMR for local tooling)

package.json

@@ -15,6 +15,7 @@
     "test:e2e": "playwright test",
     "format": "prettier --write .",
     "format:check": "prettier --check .",
+    "api:generate": "openapi-typescript http://localhost:3000/api/openapi -o types/api.ts",
     "prepare": "husky"
   },
   "lint-staged": {
@@ -78,6 +79,7 @@
     "husky": "^9.1.7",
     "jsdom": "^30.1.0",
     "lint-staged": "^17.5.1",
+    "openapi-typescript": "^7.13.0",
     "prettier": "^3.9.8",
     "prettier-plugin-tailwindcss": "^0.8.1",
     "tailwindcss": "^4",