test(coverage): exercise PingExecutor run_ping branches via loopback

Adds an untagged loopback test (127.0.0.1) so System.cmd /
Task.async / Task.yield branches in run_ping/3 are covered in CI
runs that exclude :network-tagged tests.

test/towerops/monitoring/executors/ping_executor_test.exs

@@ -62,6 +62,16 @@ defmodule Towerops.Monitoring.Executors.PingExecutorTest do
       assert is_binary(reason)
     end
 
+    test "exercises run_ping path against loopback (no network required)" do
+      # 127.0.0.1 is always reachable via loopback; this drives the
+      # System.cmd/Task.async/Task.yield branches that the :network-
+      # tagged tests cover but which CI excludes by default.
+      config = %{"host" => "127.0.0.1", "count" => 1}
+
+      result = PingExecutor.execute(config, 2000)
+      assert match?({:ok, _, _}, result) or match?({:error, _}, result)
+    end
+
     test "clamps count to range [1, 10]" do
       # Verified indirectly via build_args: clamp to 10 when given 999
       args_high = PingExecutor.build_args("127.0.0.1", 10, 5000)