Add settingsSchema (default session provider/model, enabled stages, sync
reconcile-on-hooks toggle, reconcile cadence hint) aligned across manifest.json
and the runtime manifest, with typed getters. Wire the consumed getters:
orchestrator passes defaultProvider/defaultModelId into sessions and rejects
disabled stages; hooks gate their reconcile drain on reconcileOnHooks. Add the
plugin README and docs/plugins/compound-engineering.md documenting the hub,
interactive sessions, work bridge, and the sync ownership model.
reconcileIntervalMinutes is exposed as an operator cadence hint but not yet
consumed (no host scheduler; reconcile is on-demand by design).
