Initial commit: Theriapolis baseline at port/godot branch point

Captures the pre-Godot-port state of the codebase. This is the rollback
anchor for the Godot port (M0 of theriapolis-rpg-implementation-plan-godot-port.md).
All Phase 0 through Phase 6.5 work is included; Phase 7 is in flight.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Theriapolis.Tests/Combat/EncounterTriggerTests.cs

@@ -0,0 +1,73 @@
+using Theriapolis.Core;
+using Theriapolis.Core.Data;
+using Theriapolis.Core.Entities;
+using Theriapolis.Core.Rules.Character;
+using Theriapolis.Core.Rules.Combat;
+using Theriapolis.Core.Util;
+using Xunit;
+
+namespace Theriapolis.Tests.Combat;
+
+public sealed class EncounterTriggerTests
+{
+    private readonly ContentResolver _content = new(new ContentLoader(TestHelpers.DataDirectory));
+
+    [Fact]
+    public void FindHostileTrigger_ReturnsNullWhenNoHostiles()
+    {
+        var mgr = new ActorManager();
+        mgr.SpawnPlayer(new Vec2(100, 100));
+        Assert.Null(EncounterTrigger.FindHostileTrigger(mgr));
+    }
+
+    [Fact]
+    public void FindHostileTrigger_ReturnsNearbyHostile()
+    {
+        var mgr = new ActorManager();
+        mgr.SpawnPlayer(new Vec2(100, 100));
+        var wolf = mgr.SpawnNpc(_content.Npcs.Templates.First(t => t.Id == "wolf"),
+            new Vec2(105, 100));
+        var hit = EncounterTrigger.FindHostileTrigger(mgr);
+        Assert.Same(wolf, hit);
+    }
+
+    [Fact]
+    public void FindHostileTrigger_IgnoresHostilesPastTriggerRadius()
+    {
+        var mgr = new ActorManager();
+        mgr.SpawnPlayer(new Vec2(100, 100));
+        mgr.SpawnNpc(_content.Npcs.Templates.First(t => t.Id == "wolf"),
+            new Vec2(100 + C.ENCOUNTER_TRIGGER_TILES + 5, 100));
+        Assert.Null(EncounterTrigger.FindHostileTrigger(mgr));
+    }
+
+    [Fact]
+    public void FindHostileTrigger_IgnoresFriendlyAndNeutral()
+    {
+        var mgr = new ActorManager();
+        mgr.SpawnPlayer(new Vec2(100, 100));
+        var merchant = _content.Npcs.Templates.First(t => t.Id == "merchant_traveler");
+        mgr.SpawnNpc(merchant, new Vec2(102, 100));
+        Assert.Null(EncounterTrigger.FindHostileTrigger(mgr));
+    }
+
+    [Fact]
+    public void FindInteractCandidate_FindsFriendlyOrNeutralInRange()
+    {
+        var mgr = new ActorManager();
+        mgr.SpawnPlayer(new Vec2(100, 100));
+        var merchant = _content.Npcs.Templates.First(t => t.Id == "merchant_traveler");
+        var npc = mgr.SpawnNpc(merchant, new Vec2(101, 100));
+        var hit = EncounterTrigger.FindInteractCandidate(mgr);
+        Assert.Same(npc, hit);
+    }
+
+    [Fact]
+    public void FindInteractCandidate_IgnoresHostiles()
+    {
+        var mgr = new ActorManager();
+        mgr.SpawnPlayer(new Vec2(100, 100));
+        mgr.SpawnNpc(_content.Npcs.Templates.First(t => t.Id == "wolf"), new Vec2(101, 100));
+        Assert.Null(EncounterTrigger.FindInteractCandidate(mgr));
+    }
+}