Implement assert has-past

MultiversalDiplomacy/Script/AdjudicationQueryScriptHandler.cs

@@ -101,7 +101,19 @@ public class AdjudicationQueryScriptHandler(
                 return ScriptResult.Succeed(this);
 
             case "has-past":
-                // Assert a timeline's past
+                Regex hasPast = new($"^([a-z]+[0-9]+)>([a-z]+[0-9]+)$");
+                Match hpMatch = hasPast.Match(args[1]);
+                if (!hpMatch.Success) return ScriptResult.Fail("Expected format s1>s2", this);
+
+                Season future = new(hpMatch.Groups[1].Value);
+                if (!World.Timelines.Pasts.TryGetValue(future.Key, out Season? actual)) {
+                    return ScriptResult.Fail($"No such season \"{future}\"");
+                }
+
+                Season expected = new(hpMatch.Groups[2].Value);
+                if (actual != expected) return ScriptResult.Fail(
+                    $"Expected past of {future} to be {expected}, but it was {actual}");
+                return ScriptResult.Succeed(this);
 
             case "holds":
                 // Assert a unit successfully held

MultiversalDiplomacyTests/ReplTest.cs

@@ -116,7 +116,6 @@ public class ReplTest
     [Test]
     public void AssertSeasonPast()
     {
-        Assert.Ignore();
         var repl = StandardRepl();
 
         repl.ExecuteAll("""