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)

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  quality:
+    name: lint + typecheck + test + build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Set up Bun
+        uses: oven-sh/setup-bun@v2
+        with:
+          bun-version: "1.3.14"
+
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+
+      - name: Lint
+        run: bun run lint
+
+      - name: Typecheck
+        run: bun run typecheck
+
+      - name: Unit tests
+        run: bun run test
+
+      - name: Build
+        run: bun run build
+
+      - name: Format check
+        run: bun run format:check