Add placeholder fleet status check

harborwatch/checks.py

@@ -0,0 +1,6 @@
+"""Fleet status checks."""
+
+
+def fleet_status(service_name):
+    # Placeholder until the real deploy API client is wired up.
+    return f"{service_name}: status check not yet implemented"

tests/test_checks.py

@@ -0,0 +1,5 @@
+from harborwatch.checks import fleet_status
+
+
+def test_placeholder_status():
+    assert "not yet implemented" in fleet_status("routeforge")