draft options working; spells won't cast though

Assets/_Project/Scripts/Gameplay/SpellHotkeys.cs

@@ -0,0 +1,29 @@
+// Assets/_Project/Scripts/Gameplay/SpellHotkeys.cs
+using UnityEngine.InputSystem;
+
+namespace TD.Gameplay
+{
+    /// <summary>
+    /// The fixed key bound to each spell hotkey slot (slot index == grant order ==
+    /// <see cref="PlayerSpellLoadout"/> list index). Shared by
+    /// <see cref="BuilderSpellCastController"/> (reads input) and the HUD hotbar (renders key
+    /// labels) so the two can never drift apart.
+    /// </summary>
+    /// <remarks>
+    /// <see cref="TD.UI.HUDController"/>'s <c>HotkeyLayout</c> already claims the entire
+    /// Q/W/E/R/T/A/S/D/F/G/Z/X/C/V/B block for the build command grid, so spell casting uses
+    /// the number row instead.
+    /// </remarks>
+    public static class SpellHotkeys
+    {
+        public static readonly Key[] Layout =
+        {
+            Key.Digit1,
+            Key.Digit2,
+            Key.Digit3,
+            Key.Digit4,
+        };
+
+        public static int MaxSpellSlots => Layout.Length;
+    }
+}