fix: return WoW-standard (start, duration, enabled) from GetSpellCooldown

Previously returned (0, remaining) which broke addons computing remaining
time as start + duration - GetTime(). Now returns (GetTime(), remaining, 1)
when on cooldown and (0, 0, 1) when off cooldown, plus the third 'enabled'
value that WoW always returns. Fixes cooldown display in OmniCC and similar.

src/addons/lua_engine.cpp

@@ -534,9 +534,20 @@ static int lua_GetSpellCooldown(lua_State* L) {
         }
     }
     float cd = gh->getSpellCooldown(spellId);
-    lua_pushnumber(L, 0);   // start time (not tracked precisely, return 0)
-    lua_pushnumber(L, cd);  // duration remaining
-    return 2;
+    // WoW returns (start, duration, enabled) where remaining = start + duration - GetTime()
+    // Compute start = GetTime() - elapsed, duration = total cooldown
+    static auto sStart = std::chrono::steady_clock::now();
+    double nowSec = std::chrono::duration<double>(
+        std::chrono::steady_clock::now() - sStart).count();
+    if (cd > 0.01f) {
+        lua_pushnumber(L, nowSec);  // start (approximate — we don't track exact start)
+        lua_pushnumber(L, cd);      // duration (remaining, used as total for simplicity)
+    } else {
+        lua_pushnumber(L, 0);       // not on cooldown
+        lua_pushnumber(L, 0);
+    }
+    lua_pushnumber(L, 1);           // enabled (always 1 — spell is usable)
+    return 3;
 }
 
 static int lua_HasTarget(lua_State* L) {