Add woodland atmosphere, interaction cues and scene restoration

src/World/RpgInteractionCue.cs

@@ -0,0 +1,44 @@
+namespace Cthangover.Mods.Rpg
+{
+    using Godot;
+
+    /// <summary>Highlights exactly the event the action key will run. Uses the view's target selection, so hints cannot disagree with input.</summary>
+    public partial class RpgInteractionCue : Node2D
+    {
+        private readonly RpgWorldView view;
+        private float elapsed;
+
+        /// <summary>Attaches to one map; no subscriptions or state survive unmount.</summary>
+        public RpgInteractionCue(RpgWorldView view)
+        {
+            this.view = view;
+            Name = "InteractionCue";
+        }
+
+        /// <summary>Redraws the small corner marker while an action event is in reach.</summary>
+        public override void _Process(double delta)
+        {
+            elapsed += (float)delta;
+            QueueRedraw();
+        }
+
+        /// <summary>Draws four corners around the target cell, hidden whenever another UI owns input.</summary>
+        public override void _Draw()
+        {
+            if (RpgInput.IsWalkBlocked(this))
+                return;
+            var target = view.InteractionTarget();
+            if (target == null)
+                return;
+            var rect = new Rect2(target.Position + new Vector2(2, 2), new Vector2(view.TileSize - 4, view.TileSize - 4));
+            var color = new Color(1f, 0.83f, 0.48f, 0.65f + 0.2f * Mathf.Sin(elapsed * 3));
+            foreach (var corner in new[] { rect.Position, new Vector2(rect.End.X, rect.Position.Y), rect.End, new Vector2(rect.Position.X, rect.End.Y) })
+            {
+                var dx = corner.X == rect.Position.X ? 5 : -5;
+                var dy = corner.Y == rect.Position.Y ? 5 : -5;
+                DrawLine(corner, corner + new Vector2(dx, 0), color);
+                DrawLine(corner, corner + new Vector2(0, dy), color);
+            }
+        }
+    }
+}