Adding big batch of structural code provided by Claude to start designing levels

Assets/_Project/Levels/GoalVolume.cs

@@ -0,0 +1,66 @@
+using UnityEngine;
+using TD.Core;
+
+#if UNITY_EDITOR
+using UnityEditor;
+#endif
+
+namespace TD.Levels
+{
+    /// <summary>
+    /// Authoring volume marking the win-condition target. Enemies that reach a goal volume reduce
+    /// the shared player life pool. Goal tiles are <see cref="PlacementState.Restricted"/> in the
+    /// baked grid but remain walkable so enemies can enter them.
+    /// </summary>
+    /// <remarks>
+    /// Goals have no ownership — they are shared across all players. Multiple goal volumes are
+    /// allowed; the designer specifies the expected count via
+    /// <see cref="LevelAuthoring.expectedGoalCount"/> and the bake validates the count matches.
+    ///
+    /// Final defenders are identified by their player zone being 4-adjacent to a goal volume's
+    /// tile coverage; they do not have a LeakExitVolume.
+    /// </remarks>
+    public class GoalVolume : VolumeBase
+    {
+        [Tooltip("Whether tiles in this volume are buildable. Defaults to Invalid.")]
+        public PlacementValidity placementValidity = PlacementValidity.Invalid;
+
+        // Goals draw above player zones to be visually anchoring landmarks. Higher alpha than
+        // other volume types (60% per gizmo design).
+        private const float FillYLevel = 0.04f;
+
+        protected override bool GetAlwaysShowToggle(LevelAuthoring authoring)
+        {
+            return authoring.alwaysShowGoals;
+        }
+
+        private void OnDrawGizmosSelected()
+        {
+            DrawGizmosCore();
+        }
+
+        private void OnDrawGizmos()
+        {
+            if (ShouldDrawAlwaysOn())
+            {
+                DrawGizmosCore();
+            }
+        }
+
+        private void DrawGizmosCore()
+        {
+            Color goalColor = PlayerColors.Goal;
+            DrawTileCoverageFill(goalColor, alpha: 0.60f, yLevel: FillYLevel);
+            DrawRectangularOutline(goalColor, yLevel: FillYLevel);
+
+#if UNITY_EDITOR
+            var col = Collider;
+            if (col != null)
+            {
+                Vector3 labelPos = new Vector3(col.bounds.center.x, FillYLevel + 0.1f, col.bounds.center.z);
+                Handles.Label(labelPos, "GOAL");
+            }
+#endif
+        }
+    }
+}