Complete SOLID domain ownership remediation

[smiggleworth]

Summary

• enforce family-owned domain state and crate-private composition boundaries
• confine async orchestration and Midge access to the intended edges
• preserve wire, storage, routing, acknowledgement, and restart semantics
• add golden protocol/storage fixtures, architecture contracts, and benchmark evidence

Validation

• cargo fmt --all -- --check
• cargo test --locked --workspace
• cargo test --locked --doc
• PROPTEST_CASES=256 cargo test --locked --lib state_model
• cargo clippy --locked --workspace --all-targets --all-features -- -D warnings -D clippy::pedantic
• architecture contract: 12/12
• TCP and WebSocket E2E for all seven domains
• git diff --check

Benchmark results: docs/development/solid-remediation-benchmark-report.md