feat(ACTIVITY-WP-0029): inventory callers, retarget sweep, bound execution

Map every State Hub/core-hub caller to a post-retirement owner. Keep the
15-minute sweep schedule here and point the engine at repo-manager
(State Hub dual-run by default, REPO_MANAGER_URL when present). Publish
GET /execution/semantics and 410 workplan launch routes so State Hub
/execution/* is not re-homed as a task database. T03 still waits on
HUB-WP-0004.

tests/test_execution_api.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+from activity_core.execution_api import router
+
+
+def _client() -> TestClient:
+    app = FastAPI()
+    app.include_router(router)
+    return TestClient(app)
+
+
+def test_execution_semantics_names_boundary() -> None:
+    client = _client()
+    response = client.get("/execution/semantics")
+    assert response.status_code == 200
+    body = response.json()
+    assert body["port"] == "port.schedule"
+    assert any("ops_run" in item for item in body["activity_core_owns"])
+    assert any("workplan" in item.lower() for item in body["activity_core_does_not_own"])
+    assert body["replacements"]["GET /execution/launch-requests"] == "GET /ops-runs"
+
+
+def test_execution_workplan_routes_are_gone() -> None:
+    client = _client()
+    gone = [
+        client.get("/execution/launch-requests"),
+        client.post("/execution/launch-requests", json={"workplan_id": "x"}),
+        client.get("/execution/workplan-stack"),
+        client.patch("/execution/workplans/abc/intent", json={}),
+        client.patch("/execution/workstreams/abc/intent", json={}),
+    ]
+    for response in gone:
+        assert response.status_code == 410
+        payload = response.json()
+        assert "replacement_ref" in payload
+        assert "execution-queue-boundary" in payload["document"]