Ding watch preview

The default ding binary now runs persistent watches. It supports HTTP, command and authenticated push sources; typed and numeric conditions; transition/recovery, change, provider event and missing-data policies; SQLite state/evidence; and durable console/webhook/Slack/Discord delivery.

This is an architectural cutover. run, legacy serve, test-rule and install provide migration guidance instead of running the old engine. Use the hardened v0.14.0 release for legacy workloads. ding migrate writes supported manifests and an explicit per-rule report; it does not start them or import legacy snapshots.

No watch stable release or performance capacity is declared by these notes. Review the qualification report and release checklist before tagging artifacts.