chore: phase 4 protocol adapter boundary

[Lythaeon]

Summary

• Implement Phase 4 of the hexagonal migration by replacing protocol runtime switching with registry-driven transport adapters.
• Move protocol selection flow to domain ProtocolKind across planning and local-run execution seams.
• Keep behavior stable while preserving existing protocol runtime setup functions behind adapter boundaries.

Changes

• Added TransportAdapter and updated ProtocolRegistry to register and dispatch adapters keyed by domain::run::ProtocolKind.
• Refactored builtin protocol registrations to carry protocol metadata plus sender setup callbacks; removed central runtime match dispatch.
• Threaded domain protocol selection through local run orchestration (LocalRunExecutionCommand, TrafficPort, runtime traffic adapter).
• Added explicit CLI-to-domain conversion helpers for protocol/load mode and switched plan-time protocol validation to domain keys.
• Updated protocol registry/runtime tests and local-run tests for the new transport dispatch signature.
• Marked Phase 4 artifacts as implemented in docs/architecture/ard/ARCHITECTURE_RISKS_HEXAGONAL_PLAN.md.

Checks

• cargo make format
• cargo make clippy
• cargo make test
• cargo make architecture-check
• cargo make test-wasm (not applicable)
• cargo make audit (not applicable)
• cargo make deny (not applicable)