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)

app/api/auth/[...all]/route.ts

@@ -0,0 +1,4 @@
+import { auth } from "@/lib/auth";
+import { toNextJsHandler } from "better-auth/next-js";
+
+export const { GET, POST } = toNextJsHandler(auth);

app/api/health/route.ts

@@ -0,0 +1,12 @@
+import { NextResponse } from "next/server";
+
+export const runtime = "nodejs";
+export const dynamic = "force-dynamic";
+
+export function GET() {
+  return NextResponse.json({
+    ok: true,
+    service: "nextjs-template",
+    timestamp: new Date().toISOString(),
+  });
+}

app/api/openapi/route.ts

@@ -0,0 +1,63 @@
+import { NextResponse } from "next/server";
+
+export const runtime = "nodejs";
+export const dynamic = "force-dynamic";
+
+/**
+ * Minimal OpenAPI document describing the template's own API routes.
+ * Kept in sync with app/api/** — regenerate client types with:
+ *   bun run api:generate
+ */
+export function GET() {
+  return NextResponse.json({
+    openapi: "3.1.0",
+    info: {
+      title: "Next.js Template API",
+      version: "0.1.0",
+    },
+    paths: {
+      "/api/health": {
+        get: {
+          operationId: "getHealth",
+          responses: {
+            "200": {
+              description: "Service health",
+              content: {
+                "application/json": {
+                  schema: {
+                    type: "object",
+                    properties: {
+                      ok: { type: "boolean" },
+                      service: { type: "string" },
+                      timestamp: { type: "string", format: "date-time" },
+                    },
+                    required: ["ok", "service", "timestamp"],
+                  },
+                },
+              },
+            },
+          },
+        },
+      },
+      "/api/auth/{action}": {
+        parameters: [
+          {
+            name: "action",
+            in: "path",
+            required: true,
+            schema: { type: "string" },
+          },
+        ],
+        get: {
+          operationId: "authAction",
+          responses: {
+            "200": {
+              description: "Auth route (Better Auth handler)",
+              content: { "application/json": { schema: { type: "object" } } },
+            },
+          },
+        },
+      },
+    },
+  });
+}