Recover abandoned agent turns as interrupted

Status: accepted

When session resume finds a persisted non-root turn in starting, running, or an interaction or agent wait without a surviving request, recovery settles that turn as interrupted. It releases capacity, preserves the agent identity, conversation, compaction state, and unread mailbox, enqueues one interruption RESULT to the spawn parent, and leaves the agent idle for a later follow-up. Mevedel never retries an abandoned turn automatically because its tools may already have produced side effects.