game/rendering: play SpellCast animation during SMSG_SPELL_START

Add SpellCastAnimCallback to GameHandler, triggered on SMSG_SPELL_START
(start=true) and cleared on SMSG_SPELL_GO / SMSG_SPELL_FAILURE
(start=false) for both the player and other units.

Connect the callback in Application to play animation 3 (SpellCast) on
the player character, NPCs, and other players when they begin a cast.
The cast animation is one-shot (loop=false) so it auto-returns to Stand
when complete via the existing return-to-idle logic.

Also fire stop-cast on spell failure to cancel any stuck cast pose.

include/game/game_handler.hpp

@@ -623,6 +623,11 @@ public:
     using MeleeSwingCallback = std::function<void()>;
     void setMeleeSwingCallback(MeleeSwingCallback cb) { meleeSwingCallback_ = std::move(cb); }
 
+    // Spell cast animation callbacks — true=start cast/channel, false=finish/cancel
+    // guid: caster (may be player or another unit), isChannel: channel vs regular cast
+    using SpellCastAnimCallback = std::function<void(uint64_t guid, bool start, bool isChannel)>;
+    void setSpellCastAnimCallback(SpellCastAnimCallback cb) { spellCastAnimCallback_ = std::move(cb); }
+
     // NPC swing callback (plays attack animation on NPC)
     using NpcSwingCallback = std::function<void(uint64_t guid)>;
     void setNpcSwingCallback(NpcSwingCallback cb) { npcSwingCallback_ = std::move(cb); }
@@ -2246,6 +2251,7 @@ private:
     NpcAggroCallback npcAggroCallback_;
     NpcRespawnCallback npcRespawnCallback_;
     MeleeSwingCallback meleeSwingCallback_;
+    SpellCastAnimCallback spellCastAnimCallback_;
     NpcSwingCallback npcSwingCallback_;
     NpcGreetingCallback npcGreetingCallback_;
     NpcFarewellCallback npcFarewellCallback_;

src/core/application.cpp

@@ -2762,6 +2762,38 @@ void Application::setupUICallbacks() {
         }
     });
 
+    // Spell cast animation callback — play cast animation on caster (player or NPC/other player)
+    gameHandler->setSpellCastAnimCallback([this](uint64_t guid, bool start, bool /*isChannel*/) {
+        if (!renderer) return;
+        auto* cr = renderer->getCharacterRenderer();
+        if (!cr) return;
+        // Animation 3 = SpellCast (one-shot; return-to-idle handled by character_renderer)
+        const uint32_t castAnim = 3;
+        // Check player character
+        {
+            uint32_t charInstId = renderer->getCharacterInstanceId();
+            if (charInstId != 0 && guid == gameHandler->getPlayerGuid()) {
+                if (start) cr->playAnimation(charInstId, castAnim, false);
+                // On finish: playAnimation(castAnim, loop=false) will auto-return to Stand
+                return;
+            }
+        }
+        // Check creatures and other online players
+        {
+            auto it = creatureInstances_.find(guid);
+            if (it != creatureInstances_.end()) {
+                if (start) cr->playAnimation(it->second, castAnim, false);
+                return;
+            }
+        }
+        {
+            auto it = playerInstances_.find(guid);
+            if (it != playerInstances_.end()) {
+                if (start) cr->playAnimation(it->second, castAnim, false);
+            }
+        }
+    });
+
     // NPC greeting callback - play voice line
     gameHandler->setNpcGreetingCallback([this](uint64_t guid, const glm::vec3& position) {
         if (renderer && renderer->getNpcVoiceManager()) {

src/game/game_handler.cpp

@@ -2605,9 +2605,15 @@ void GameHandler::handlePacket(network::Packet& packet) {
                         ssm->stopPrecast();
                     }
                 }
+                if (spellCastAnimCallback_) {
+                    spellCastAnimCallback_(playerGuid, false, false);
+                }
             } else {
                 // Another unit's cast failed — clear their tracked cast bar
                 unitCastStates_.erase(failGuid);
+                if (spellCastAnimCallback_) {
+                    spellCastAnimCallback_(failGuid, false, false);
+                }
             }
             break;
         }
@@ -12949,6 +12955,10 @@ void GameHandler::handleSpellStart(network::Packet& packet) {
         s.spellId       = data.spellId;
         s.timeTotal     = data.castTime / 1000.0f;
         s.timeRemaining = s.timeTotal;
+        // Trigger cast animation on the casting unit
+        if (spellCastAnimCallback_) {
+            spellCastAnimCallback_(data.casterUnit, true, false);
+        }
     }
 
     // If this is the player's own cast, start cast bar
@@ -12970,6 +12980,11 @@ void GameHandler::handleSpellStart(network::Packet& packet) {
             }
         }
 
+        // Trigger cast animation on player character
+        if (spellCastAnimCallback_) {
+            spellCastAnimCallback_(playerGuid, true, false);
+        }
+
         // Hearthstone cast: begin pre-loading terrain at bind point during cast time
         // so tiles are ready when the teleport fires (avoids falling through un-loaded terrain).
         // Spell IDs: 6948 = Vanilla Hearthstone (rank 1), 8690 = TBC/WotLK Hearthstone
@@ -13021,6 +13036,14 @@ void GameHandler::handleSpellGo(network::Packet& packet) {
         casting = false;
         currentCastSpellId = 0;
         castTimeRemaining = 0.0f;
+
+        // End cast animation on player character
+        if (spellCastAnimCallback_) {
+            spellCastAnimCallback_(playerGuid, false, false);
+        }
+    } else if (spellCastAnimCallback_) {
+        // End cast animation on other unit
+        spellCastAnimCallback_(data.casterUnit, false, false);
     }
 
     // Clear unit cast bar when the spell lands (for any tracked unit)