- Overhaul .check.exs to match ops_center pattern (compiler, deps_unlock, test, audit)
- Add cli/0 with preferred_envs so mix check runs in test env automatically
- Add clean to check alias to prevent stale BEAM artifacts on OTP 28
- Fix coding_agent_test to use module_info(:exports) instead of function_exported?/3
  which returns false for stale BEAM code on OTP 28
- Handle DBConnection ownership errors in embedder gracefully
- Add missing @impl true annotation on CodingAgent.summarize/2
- Fix unused variable warning in Git.summarize/2