feat: add minimal runtime service registry seam

[skylarbpayne]

Scope

• add the version-1 process-local runtime service registry contract
• require integration-owned registries to opt into the nominal RuntimeOnlyServiceRegistry marker while still implementing RuntimeServiceRegistry
• preserve marked caller registries by identity without mutation or wrapping; reject unmarked structural registries at engine construction
• reject marked registries at the shared framework JSON boundary so nested artifact, status, and SQLite/event persistence paths fail closed
• retain built-in JSON/pickle TypeError behavior without claiming blanket pickle refusal for arbitrary unmarked third-party objects

Verification

• expected red: ImportError: cannot import name 'RuntimeOnlyServiceRegistry' (1 error, exit 2)
• focused: uv run pytest -q tests/test_runtime_services_contract.py tests/test_engine.py tests/test_runner_v2_recovery.py tests/test_types.py (39 passed)
• full: uv run pytest -q (462 passed, 2 skipped)
• git diff --check: clean
• exact allowlist: src/hermes_workflows/runtime_services.py, src/hermes_workflows/engine.py, src/hermes_workflows/types.py, tests/test_runtime_services_contract.py

Base and amendment receipt

• previous reviewed head: 0e86026e2688466056d3fdcc7d3249ed9f685b75
• incorporated current origin/main at 2727a46b1a799a4a2125d3b85e292db514f1fb98 without consuming stale PR feat: support custom select values in review queue #131
• amended head: adbf605c201edd3839864357b7c51ddfd17aac48
• implements Skylar-approved FND-RT amendment A from canonical plan SHA-256 3d65b30324b52dfd4b7de3044bddf9e7e63339c439bf53b27f603466ec6cf72b

[skylarbpayne]

SR9 overlap repair pushed at 4cc4549fce268d109b1fe2d0698a9438e7930d34.

• Traverses every applicable dataclass/Mapping/Sequence/Set shape under one active-ID cycle guard.
• Uses indexed Sequence traversal so Mapping+Sequence hybrids cannot hide runtime registries behind Mapping iteration.
• Added direct serializer + real SQLite/event persistence regressions, including cycle and secret non-leak checks.
• Focused: 53 passed.
• Full Python 3.11: 477 passed, 1 skipped.
• Full Python 3.9 isolated: 477 passed, 1 skipped.
• git diff --check clean; exact four-path allowlist preserved.