Refactor module consumers onto direct mc-host boundary

[ahrav]

Summary

• internalize version-2 wire, authentication, secure discovery, control, and managed Rust client contracts in mc-host
• adapt McHandler, historian, resolver, Synapse, and Broca consumers to direct host-owned lifecycle and route APIs
• reserve successful module response capacity before encoding and drain module-owned work on shutdown
• rename TypeScript callers to McHost*, require strict negotiation/version handling, and remove compatibility aliases
• replace provider/sibling-workspace Rust and E2E topology with owner-only direct-host fixtures
• remove Rust/npm subc-* dependencies, old ck-mc binary, stale fixtures, and compatibility documentation

Verification

• cargo test --workspace
• cargo fmt --check
• cargo clippy --workspace --all-targets -- -D warnings
• bun run --cwd packages/plugin test
• bun run --cwd packages/plugin typecheck
• bun run --cwd packages/cli typecheck
• bunx tsc --noEmit -p packages/e2e-tests/tsconfig.json
• focused direct-host fixture, Rust smoke, historian, manifest, and static boundary suites
• dependency/source closure scans

Review

Parallel invariant-test, TypeScript, Rust, and complexity reviews completed. Findings fixed and re-reviewed. Final ponytail review applied safe deletions.

Deferred

Production launcher/configuration/doctor lifecycle remains with magic-context-c50.8. Broad Rust E2E, mutation, performance, and release qualification remain with magic-context-c50.9.

Summary by CodeRabbit

• New Features

  • Rust transform mode now connects directly to the mc-host runtime.
  • Added managed client support for authenticated unary and streaming requests, cancellation, deadlines, retries, and binary responses.
  • Added secure connection-file discovery with strict protocol, permissions, and credential validation.
  • Added direct-host end-to-end testing and lifecycle controls.

• Bug Fixes

  • Improved handling of timeouts, reconnects, cancellation races, backpressure, shutdown, and oversized or malformed messages.
  • Improved error classification and redaction of sensitive host details.

• Documentation

  • Updated architecture, protocol, migration, deployment, and Rust testing guidance for the direct host runtime.