Wire the composition root: flags, providers, runnables, manifests, samples, docs

Co-Authored-By: Claude <noreply@anthropic.com>

hack/providers-dev.yaml

@@ -0,0 +1,6 @@
+# Providers config for `make run-dev`: local development against the
+# current kubeconfig context (e.g. a kind cluster). Only the
+# kubernetes-pod provider — no cloud credentials needed.
+providers:
+  - name: kubernetes
+    type: kubernetes