dsh-phoenix 0.2.0

Durable lifecycle & safe-restart semantics. Explicit state machine (idle/deferred/restarting/recovering/running) with atomic checkpoint; resume is at-most-once per generation (durable resumeAttempt before the call); stale/corrupt checkpoints are invalidated, not resumed; in-flight restarts coalesce; defer timeout is now a soft->warn->hard deadline (policy auto/wait); 17 failure-injection tests (crash/stale/duplicate/failure/loop prevention).