add limits to steal objectives (#22672)

* add ObjectiveLimit comp/system

* give ian and disk limits

* all

* up limit

---------

Co-authored-by: deltanedas <@deltanedas:kde.org>

Content.Server/Objectives/Systems/ObjectiveLimitSystem.cs

@@ -0,0 +1,64 @@
+using Content.Server.GameTicking.Rules.Components;
+using Content.Server.Objectives.Components;
+using Content.Shared.Mind;
+using Content.Shared.Objectives.Components;
+
+public sealed class ObjectiveLimitSystem : EntitySystem
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<ObjectiveLimitComponent, RequirementCheckEvent>(OnCheck);
+    }
+
+    private void OnCheck(Entity<ObjectiveLimitComponent> ent, ref RequirementCheckEvent args)
+    {
+        if (args.Cancelled)
+            return;
+
+        if (Prototype(ent)?.ID is not {} proto)
+        {
+            Log.Error($"ObjectiveLimit used for non-prototyped objective {ent}");
+            return;
+        }
+
+        var remaining = ent.Comp.Limit;
+        // all traitor rules are considered
+        // maybe this would interfere with multistation stuff in the future but eh
+        foreach (var rule in EntityQuery<TraitorRuleComponent>())
+        {
+            foreach (var mindId in rule.TraitorMinds)
+            {
+                if (mindId == args.MindId || !HasObjective(mindId, proto))
+                    continue;
+
+                remaining--;
+
+                // limit has been reached, prevent adding the objective
+                if (remaining == 0)
+                {
+                    args.Cancelled = true;
+                    return;
+                }
+            }
+        }
+    }
+
+    /// <summary>
+    /// Returns true if the mind has an objective of a certain prototype.
+    /// </summary>
+    public bool HasObjective(EntityUid mindId, string proto, MindComponent? mind = null)
+    {
+        if (!Resolve(mindId, ref mind))
+            return false;
+
+        foreach (var objective in mind.AllObjectives)
+        {
+            if (Prototype(objective)?.ID == proto)
+                return true;
+        }
+
+        return false;
+    }
+}