feat: add spell power cost to SpellDataResolver; fix IsUsableSpell mana check

Extend SpellDataInfo with manaCost and powerType fields, extracted from
Spell.dbc ManaCost and PowerType columns. This enables IsUsableSpell()
to properly check if the player has enough mana/rage/energy to cast.

Previously IsUsableSpell always returned notEnoughMana=false since cost
data wasn't available. Now it compares the spell's DBC mana cost against
the player's current power, returning accurate usability and mana state.

This fixes action bar addons showing abilities as usable when the player
lacks sufficient power, and enables OmniCC-style cooldown text to
properly dim insufficient-power abilities.

src/addons/lua_engine.cpp

@@ -2189,8 +2189,22 @@ static int lua_IsUsableSpell(lua_State* L) {
     float cd = gh->getSpellCooldown(spellId);
     bool onCooldown = (cd > 0.1f);
 
-    lua_pushboolean(L, onCooldown ? 0 : 1);  // usable (not on cooldown)
-    lua_pushboolean(L, 0);  // noMana (can't determine without spell cost data)
+    // Check mana/power cost
+    bool noMana = false;
+    if (!onCooldown) {
+        auto spellData = gh->getSpellData(spellId);
+        if (spellData.manaCost > 0) {
+            auto playerEntity = gh->getEntityManager().getEntity(gh->getPlayerGuid());
+            if (playerEntity) {
+                auto* unit = dynamic_cast<game::Unit*>(playerEntity.get());
+                if (unit && unit->getPower() < spellData.manaCost) {
+                    noMana = true;
+                }
+            }
+        }
+    }
+    lua_pushboolean(L, (onCooldown || noMana) ? 0 : 1);  // usable
+    lua_pushboolean(L, noMana ? 1 : 0);                    // notEnoughMana
     return 2;
 }