[tryuan99]

As title. The IsPursuable property is needed because a target's pursuers should only contain pursuable hierarchical objects instead of also non-pursuable hierarchical objects such as clusters.

[daniellovell]

Recommend add tests for HierAgent that mock the IAgent interface to test both IsPursuable states, e.g.

[Test]
public void Target_WhenIsPursuableTrue_AddsToPursuers() {
  var mockAgent = CreateMockAgent(isPursuable: true);
  var hierarchicalAgent = new HierarchicalAgent(mockAgent);
  var target = new HierarchicalBase();

  hierarchicalAgent.Target = target;

  Assert.Contains(hierarchicalAgent, target.Pursuers);
}

[Test]
public void Target_WhenIsPursuableFalse_DoesNotAddToPursuers() {
  var mockAgent = CreateMockAgent(isPursuable: false);
  var hierarchicalAgent = new HierarchicalAgent(mockAgent);
  var target = new HierarchicalBase();

  hierarchicalAgent.Target = target;

  Assert.IsFalse(target.Pursuers.Contains(hierarchicalAgent));
}

[daniellovell]

Later PRs address everything that wasn't already addressed, looks great