add Rivet Actors host

[advait]

What changed

• add effect-durable-agent-rivet, a native Rivet Actors host with actor-local SQLite persistence, lifecycle recovery, keepAwake integration, typed actions, and the shared EDA WebSocket resume/ACK protocol
• expose an application-owned authorize hook through RivetKit's onBeforeConnect boundary so submit, read, destroy, and raw WebSocket access can be scoped per session
• run the shared durable-session conformance journey against a real Rivet Engine, including hard-restart persistence, in-flight recovery, durable idempotency, warm/cold destruction, authorization rejection, and live-socket shutdown on destroy
• add examples/005-rivet-no-tools and update the root/package documentation to present Durable Objects, celld, and Rivet Actors as supported hosts
• move all four packages to 0.1.0-alpha.5 and include the Rivet package in lockstep release, packaging, and isolated-tarball consumer validation

Why

EDA's host-neutral runtime should be deployable anywhere that can provide durable per-session storage, lifecycle, and transport. Rivet Actors supply those primitives directly, so this adapter maps them to EDA ports without introducing Rivet dependencies into the core package.

The package version is intentionally synchronized with core, Cloudflare, and celld. Consumers should install matching EDA package versions.

Validation

• pnpm run ci
  • all four packages build and pass publint
  • lint and TypeScript checks pass
  • 358 unit/service/example tests pass, with one existing opt-in test skipped
  • real workerd, celld, and Rivet Engine host-conformance suites pass
  • all four 0.1.0-alpha.5 tarballs pass isolated consumer installation/typechecking
  • workspace lockstep version and package-content checks pass

Release note

effect-durable-agent-rivet is a new npm package name. Its initial npm bootstrap/trusted-publisher setup will be completed separately before the lockstep alpha.5 release.