Deepen role runtime ownership - #234

Summary

• add supported ClientRuntime and ServerRuntime process seams
• move role orchestration, mode selection, shutdown, drain, ACME, and Managed-session ownership out of CLI callers
• join Client workers and Server readiness, handshake, Visitor-intake, ACME, and session work on every terminal path
• preserve the initiating error while teardown completes
• contract binary-only crate exports and document the intentional public runtime inventory

Refs #232

Stack

• based on Deepen active Visitor work ownership #233, which supplies the Active Visitor lease and event-driven quiescence used by total Server teardown

Validation

• cargo test --all-features
• cargo clippy --all-targets --all-features -- -D warnings
• cargo fmt --check
• host actionlint
• workflow wrapper attempted; remote Docker SSH timed out
• dependency audit attempted; unchanged transitive event-listener 5.4.1 is covered by RUSTSEC-2026-0221

Review

• Standards and Spec review completed from c81c61da
• fixed Managed Client controller-first teardown, Server child joins, ACME error teardown, session drain, and public-interface inventory