Task 2: ActionButtons rework - remove manual selection, auto-transition to Meditate

src/lib/game/utils/combat-utils.ts

@@ -207,11 +207,16 @@ export function deductSpellCost(
   const newElements = { ...elements };
   
   if (cost.type === 'raw') {
-    return { rawMana: rawMana - cost.amount, elements: newElements };
+    // Don't allow rawMana to go below zero
+    const deductedAmount = Math.min(rawMana, cost.amount);
+    return { rawMana: rawMana - deductedAmount, elements: newElements };
   } else if (cost.element && newElements[cost.element]) {
+    const elem = newElements[cost.element];
+    // Don't allow elemental mana to go below zero
+    const deductedAmount = Math.min(elem.current, cost.amount);
     newElements[cost.element] = {
-      ...newElements[cost.element],
-      current: newElements[cost.element].current - cost.amount
+      ...elem,
+      current: elem.current - deductedAmount
     };
     return { rawMana, elements: newElements };
   }