fix: add docker-setup action, runtime Dockerfile, and align release workflow

- Add .github/actions/docker-setup composite action (from rivet)
- Add docker/runtime/Dockerfile for Docker image builds
- Update release.yaml to match rivet patterns:
  - Use corepack enable instead of pnpm/action-setup
  - Add reuse_engine_version input
  - Add Docker job with Depot runners
  - Use --no-frozen-lockfile for pnpm install
  - Add id-token permission for setup job

examples/vercel/vercel-sandbox.ts

@@ -2,6 +2,7 @@ import { Sandbox } from "@vercel/sandbox";
 import { pathToFileURL } from "node:url";
 import {
   ensureUrl,
+  logInspectorUrl,
   runPrompt,
   waitForHealth,
 } from "../shared/sandbox-agent-client.ts";
@@ -61,6 +62,7 @@ export async function setupVercelSandboxAgent(): Promise<{
 
   const baseUrl = ensureUrl(sandbox.domain(port));
   await waitForHealth({ baseUrl, token });
+  logInspectorUrl({ baseUrl, token });
 
   const cleanup = async () => {
     try {