Replace supervisor with agentrun worker service

Move agent-run orchestration from the legacy supervisor path into the new
agentrun worker/service package and wire it through coredata, server,
policies, and GraphQL resolvers.

This consolidates run lifecycle handling around lease-aware workers and
aligns API surface with the new agent-run domain model so reviewers can
follow one coherent execution path.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/agentrun/export_test.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package agentrun
+
+// ShutdownBroadcast returns the channel that closes once the worker has
+// broadcast graceful shutdown to all in-flight runs. It is compiled only
+// in test builds so external tests can synchronize tool release with
+// shutdown propagation without leaking a test-only method into the
+// worker's public API.
+func (w *Worker) ShutdownBroadcast() <-chan struct{} {
+	return w.handler.shutdownCh
+}