fix(Core/Spells): Prevent Flexweave Underlay use on ground (#25158)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

data/sql/updates/pending_db_world/rev_flexweave_underlay_script.sql

@@ -0,0 +1,2 @@
+DELETE FROM `spell_script_names` WHERE `spell_id` = 55002;
+INSERT INTO `spell_script_names` (`spell_id`, `ScriptName`) VALUES (55002, 'spell_item_flexweave_underlay');

src/server/scripts/Spells/spell_item.cpp

@@ -3565,6 +3565,24 @@ class spell_item_rocket_boots : public SpellScript
     }
 };
 
+// 55002 - Flexweave Underlay
+class spell_item_flexweave_underlay : public SpellScript
+{
+    PrepareSpellScript(spell_item_flexweave_underlay);
+
+    SpellCastResult CheckCast()
+    {
+        if (GetCaster()->IsFlying() || GetCaster()->IsFalling())
+            return SPELL_CAST_OK;
+        return SPELL_FAILED_NOT_FLYING;
+    }
+
+    void Register() override
+    {
+        OnCheckCast += SpellCheckCastFn(spell_item_flexweave_underlay::CheckCast);
+    }
+};
+
 class spell_item_healing_injector : public SpellScript
 {
     PrepareSpellScript(spell_item_healing_injector);
@@ -6327,6 +6345,7 @@ void AddSC_item_spell_scripts()
     RegisterSpellScript(spell_item_deathbringers_will_normal);
     RegisterSpellScript(spell_item_deathbringers_will_heroic);
     RegisterSpellScript(spell_item_discerning_eye_beast_dummy);
+    RegisterSpellScript(spell_item_flexweave_underlay);
     RegisterSpellScript(spell_item_frozen_shadoweave);
     RegisterSpellScript(spell_item_healing_touch_refund);
     RegisterSpellScript(spell_item_heartpierce);