Product updates: memory snapshotting, OIDC, async job queues & more

Introduced faster memory snapshotting for models like Stable Diffusion, cutting cold start times by half. Expanded async job queues to support up to 1 million inputs. Added OpenID Connect (OIDC) for short-lived token authentication against external resources, replacing Modal Secrets. Enabled eStargz compression for faster image builds from external registries. Updated CLI with `--detach` flag for `modal launch` and added streaming output, timeout, workdir, and secrets parameters to `Sandbox.exec`.