Brings the semantically-correct unification work from the closed
agent/release-v2-experience PR into release/v2:
- universal create surface (header, board, spotlight) with permission-aware actions
- board empty state and setup checklist with widget/connection recipes
- in-widget integration editing via inspector modal, preserving unsaved widget settings
- single-source widget-integration capability map (nativeFeatureCapabilities)
- multi-endpoint Docker singleton with per-endpoint failure isolation, DOCKER_ENDPOINTS descriptors and service reconciliation
- Kubernetes multi-context registry with availability probing and context selector
- response-contract test harness and setup analytics property boundaries
Excludes the feature-platform generator/workbench tooling (deferred).