feat(yoagent-rutis): move to rutis 0.6

[yuanhao]

Moves the unpublished yoagent-rutis bridge from rutis 0.5 to 0.6 (rutis = "0.6", resolved to 0.6.1).

What changed upstream:

• 0.5 → 0.6: public types became #[non_exhaustive]. "Services, events and plugin interfaces unchanged."
• 0.6.0 → 0.6.1: no breaking change to the core. It adds optional APIs: boxed plugins, Ctx::dispose_self, FiberView::set_config, and a ServiceChanged bus event. The plugin control plane (rutis-loader) ships as a separate crate.

What changed here:

• No source change in the bridge.
• One test builds EventOptions with EventOptions::default().prepend(true) instead of a struct literal.
• Version references are updated in Cargo.toml, lib.rs, the README, the CI comment, CLAUDE.md and the CHANGELOG.
• The bridge's liveness checks before and after dispatch (host::closed) stay. I diffed rutis's waterfall dispatch between 0.5.0 and 0.6.1: it's byte-identical and still doesn't check liveness. The comments now say "0.5 and 0.6".

Checked locally:

• fmt, clippy -Dwarnings, docs -Dwarnings;
• all 7 test binaries;
• the policy_plugin example (the rate cap and deny rule behave the same);
• the MSRV 1.86 check, mirroring CI's job including its yoke-derive pin.

A fresh review of the whole integration, and an assessment of rutis for native and Workers, are running separately. Their findings will come in follow-ups.

🤖 Generated with Claude Code

https://claude.ai/code/session_01T7iq5hpndSiHQcnAsywKuG