docs: close operational reliability roadmap

[incendiary]

Summary

• mark operational reliability PRs 170 and 171 as merged
• record that in-repository operational reliability work is complete
• leave real allocator validation and measured performance work clearly separate

Verification

• Ruff check and format check passed
• baseline: 5 passed
• full suite: 320 passed, 95% coverage for classes and imports
• Gitleaks and TruffleHog found no secrets in the commit range