feat: add GetShapeshiftFormInfo for stance/form bar display

GetShapeshiftFormInfo(index) returns icon, name, isActive, isCastable
for each shapeshift form slot. Provides complete form tables for:

- Warrior: Battle Stance, Defensive Stance, Berserker Stance
- Druid: Bear, Travel, Cat, Swift Flight, Moonkin, Tree of Life
- Death Knight: Blood/Frost/Unholy Presence
- Rogue: Stealth

isActive is true when the form matches the current shapeshiftFormId_.
GetShapeshiftFormCooldown stub returns no cooldown.

Together with GetShapeshiftForm and GetNumShapeshiftForms from the
previous commit, this completes the stance bar API that addons use
to render and interact with form/stance buttons.

src/addons/lua_engine.cpp

@@ -5013,6 +5013,60 @@ void LuaEngine::registerCoreAPI() {
         {"IsInRaid",      lua_IsInRaid},
         {"GetPlayerMapPosition", lua_GetPlayerMapPosition},
         {"GetPlayerFacing",     lua_GetPlayerFacing},
+        {"GetShapeshiftFormInfo", [](lua_State* L) -> int {
+            // GetShapeshiftFormInfo(index) → icon, name, isActive, isCastable
+            auto* gh = getGameHandler(L);
+            int index = static_cast<int>(luaL_checknumber(L, 1));
+            if (!gh || index < 1) { lua_pushnil(L); return 1; }
+            uint8_t classId = gh->getPlayerClass();
+            uint8_t currentForm = gh->getShapeshiftFormId();
+
+            // Form tables per class: {formId, spellId, name, icon}
+            struct FormInfo { uint8_t formId; const char* name; const char* icon; };
+            static const FormInfo warriorForms[] = {
+                {17, "Battle Stance", "Interface\\Icons\\Ability_Warrior_OffensiveStance"},
+                {18, "Defensive Stance", "Interface\\Icons\\Ability_Warrior_DefensiveStance"},
+                {19, "Berserker Stance", "Interface\\Icons\\Ability_Racial_Avatar"},
+            };
+            static const FormInfo druidForms[] = {
+                {1,  "Bear Form", "Interface\\Icons\\Ability_Racial_BearForm"},
+                {4,  "Travel Form", "Interface\\Icons\\Ability_Druid_TravelForm"},
+                {3,  "Cat Form", "Interface\\Icons\\Ability_Druid_CatForm"},
+                {27, "Swift Flight Form", "Interface\\Icons\\Ability_Druid_FlightForm"},
+                {31, "Moonkin Form", "Interface\\Icons\\Spell_Nature_ForceOfNature"},
+                {36, "Tree of Life", "Interface\\Icons\\Ability_Druid_TreeofLife"},
+            };
+            static const FormInfo dkForms[] = {
+                {32, "Blood Presence", "Interface\\Icons\\Spell_Deathknight_BloodPresence"},
+                {33, "Frost Presence", "Interface\\Icons\\Spell_Deathknight_FrostPresence"},
+                {34, "Unholy Presence", "Interface\\Icons\\Spell_Deathknight_UnholyPresence"},
+            };
+            static const FormInfo rogueForms[] = {
+                {30, "Stealth", "Interface\\Icons\\Ability_Stealth"},
+            };
+
+            const FormInfo* forms = nullptr;
+            int numForms = 0;
+            switch (classId) {
+                case 1: forms = warriorForms; numForms = 3; break;
+                case 6: forms = dkForms; numForms = 3; break;
+                case 4: forms = rogueForms; numForms = 1; break;
+                case 11: forms = druidForms; numForms = 6; break;
+                default: lua_pushnil(L); return 1;
+            }
+            if (index > numForms) { lua_pushnil(L); return 1; }
+            const auto& fi = forms[index - 1];
+            lua_pushstring(L, fi.icon);                          // icon
+            lua_pushstring(L, fi.name);                          // name
+            lua_pushboolean(L, currentForm == fi.formId ? 1 : 0); // isActive
+            lua_pushboolean(L, 1);                               // isCastable
+            return 4;
+        }},
+        {"GetShapeshiftFormCooldown", [](lua_State* L) -> int {
+            // No per-form cooldown tracking — return no cooldown
+            lua_pushnumber(L, 0); lua_pushnumber(L, 0); lua_pushnumber(L, 1);
+            return 3;
+        }},
         {"GetShapeshiftForm", [](lua_State* L) -> int {
             auto* gh = getGameHandler(L);
             lua_pushnumber(L, gh ? gh->getShapeshiftFormId() : 0);