refactor(service-automation): move AutomationEngine.resumeInternal's body into run-resume.ts

Move-only. The class keeps the private method, its docblock and its
signature, and calls the body with a RunResumeHost literal holding the
25 members the body reads (logger, flows, resuming and
consumedSuspensions by value; the rest as late-bound closures, so the
two recursive call sites still route through the class method).

ChildRunRefusal, isRetryableResumeRefusal, carriesSubflowChildOutput
and applyResumeSignal gain `export` in place so run-resume.ts can read
them; ENGINE_BUILT_SIGNAL stays unexported.

Claude-Session: https://claude.ai/code/session_01Rg1PtyxbtSpabeP7j6fq8Y
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude