Battle unit gauges extension point; battle action schemas

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Gauges/BattleGauge.cs

@@ -0,0 +1,24 @@
+namespace Cthangover.Core.Battle
+{
+    /// <summary>
+    /// One extra bar of a battle unit next to its health (mana, rage, ammo…), as an
+    /// <see cref="IBattleUnitGauge"/> reads it at this moment.
+    /// </summary>
+    public class BattleGauge
+    {
+        /// <summary>Stable id (a stat id, for example) the cores key their rows by.</summary>
+        public string Id { get; set; }
+
+        /// <summary>Short label, a locale key or plain text ("MP").</summary>
+        public string Label { get; set; }
+
+        /// <summary>Current value.</summary>
+        public int Current { get; set; }
+
+        /// <summary>Maximum; a bar with Max &lt;= 0 is not drawn.</summary>
+        public int Max { get; set; }
+
+        /// <summary>Fill colour as HTML ("#4a8cff"); null = the theme's info colour.</summary>
+        public string Color { get; set; }
+    }
+}