Cloudflare Sandbox SDK v0.10.3：新增无会话执行模式

Patch Changes

• #715 453b577 Thanks @aron-cf! - Upgrade capnweb to 0.8.0.
• #714 0ec4f42 Thanks @aron-cf! - Bundle cloudflared into the musl/Alpine images.
• #706 ae5f9a1 Thanks @scuffi! - Add sessionless execution mode with a configurable default-session policy.
• Set enableDefaultSession: false in SandboxOptions to run implicit top-level operations without a persistent shell — each command gets a fresh process with no shared state. The option is scoped to the sandbox object returned by getSandbox(...); explicit per-call session IDs continue to target that session.