Handle SMSG_ACHIEVEMENT_EARNED with toast banner and chat notification

- Parse SMSG_ACHIEVEMENT_EARNED (guid + achievementId + PackedTime date)
  and fire AchievementEarnedCallback for self, chat notify for others
- Add renderAchievementToast() to GameScreen: slides in from right,
  gold-bordered panel with "Achievement Earned!" title + ID, 5s duration
  with 0.4s slide-in/out animation and fade at end
- Add triggerAchievementToast(uint32_t) public method on GameScreen
- Wire AchievementEarnedCallback in application.cpp
- Add playAchievementAlert() to UiSoundManager, loads
  Sound\Interface\AchievementSound.wav with level-up fallback
- SMSG_ALL_ACHIEVEMENT_DATA silently consumed (no tracker UI yet)

include/audio/ui_sound_manager.hpp

@@ -67,6 +67,9 @@ public:
     // Level up
     void playLevelUp();
 
+    // Achievement
+    void playAchievementAlert();
+
     // Error/feedback
     void playError();
     void playTargetSelect();
@@ -114,6 +117,7 @@ private:
     std::vector<UISample> drinkingSounds_;
 
     std::vector<UISample> levelUpSounds_;
+    std::vector<UISample> achievementSounds_;
 
     std::vector<UISample> errorSounds_;
     std::vector<UISample> selectTargetSounds_;

include/game/game_handler.hpp

@@ -834,6 +834,10 @@ public:
     using OtherPlayerLevelUpCallback = std::function<void(uint64_t guid, uint32_t newLevel)>;
     void setOtherPlayerLevelUpCallback(OtherPlayerLevelUpCallback cb) { otherPlayerLevelUpCallback_ = std::move(cb); }
 
+    // Achievement earned callback — fires when SMSG_ACHIEVEMENT_EARNED is received
+    using AchievementEarnedCallback = std::function<void(uint32_t achievementId)>;
+    void setAchievementEarnedCallback(AchievementEarnedCallback cb) { achievementEarnedCallback_ = std::move(cb); }
+
     // Mount state
     using MountCallback = std::function<void(uint32_t mountDisplayId)>;  // 0 = dismount
     void setMountCallback(MountCallback cb) { mountCallback_ = std::move(cb); }
@@ -1166,6 +1170,7 @@ private:
     void handleSpellGo(network::Packet& packet);
     void handleSpellCooldown(network::Packet& packet);
     void handleCooldownEvent(network::Packet& packet);
+    void handleAchievementEarned(network::Packet& packet);
     void handleAuraUpdate(network::Packet& packet, bool isAll);
     void handleLearnedSpell(network::Packet& packet);
     void handleSupercededSpell(network::Packet& packet);
@@ -1873,6 +1878,7 @@ private:
     ChargeCallback chargeCallback_;
     LevelUpCallback levelUpCallback_;
     OtherPlayerLevelUpCallback otherPlayerLevelUpCallback_;
+    AchievementEarnedCallback achievementEarnedCallback_;
     MountCallback mountCallback_;
     TaxiPrecacheCallback taxiPrecacheCallback_;
     TaxiOrientationCallback taxiOrientationCallback_;

include/ui/game_screen.hpp

@@ -326,8 +326,15 @@ private:
     uint32_t dingLevel_ = 0;
     void renderDingEffect();
 
+    // Achievement toast banner
+    static constexpr float ACHIEVEMENT_TOAST_DURATION = 5.0f;
+    float achievementToastTimer_ = 0.0f;
+    uint32_t achievementToastId_ = 0;
+    void renderAchievementToast();
+
 public:
     void triggerDing(uint32_t newLevel);
+    void triggerAchievementToast(uint32_t achievementId);
 };
 
 } // namespace ui