rendering/game: make player model semi-transparent in ghost form

Add GhostStateCallback to GameHandler, fired when PLAYER_FLAGS_GHOST
transitions on or off in UPDATE_OBJECT / login detection. Add
setInstanceOpacity() to CharacterRenderer to directly set opacity
without disturbing fade-in state. Application wires the callback to
set opacity 0.5 on ghost entry and 1.0 on resurrect.

include/game/game_handler.hpp

@@ -624,6 +624,10 @@ public:
     using StandStateCallback = std::function<void(uint8_t standState)>;
     void setStandStateCallback(StandStateCallback cb) { standStateCallback_ = std::move(cb); }
 
+    // Ghost state callback — fired when player enters or leaves ghost (spirit) form
+    using GhostStateCallback = std::function<void(bool isGhost)>;
+    void setGhostStateCallback(GhostStateCallback cb) { ghostStateCallback_ = std::move(cb); }
+
     // Melee swing callback (for driving animation/SFX)
     using MeleeSwingCallback = std::function<void()>;
     void setMeleeSwingCallback(MeleeSwingCallback cb) { meleeSwingCallback_ = std::move(cb); }
@@ -2256,6 +2260,7 @@ private:
     NpcAggroCallback npcAggroCallback_;
     NpcRespawnCallback npcRespawnCallback_;
     StandStateCallback standStateCallback_;
+    GhostStateCallback ghostStateCallback_;
     MeleeSwingCallback meleeSwingCallback_;
     SpellCastAnimCallback spellCastAnimCallback_;
     NpcSwingCallback npcSwingCallback_;

include/rendering/character_renderer.hpp

@@ -78,6 +78,7 @@ public:
     void setInstanceRotation(uint32_t instanceId, const glm::vec3& rotation);
     void moveInstanceTo(uint32_t instanceId, const glm::vec3& destination, float durationSeconds);
     void startFadeIn(uint32_t instanceId, float durationSeconds);
+    void setInstanceOpacity(uint32_t instanceId, float opacity);
     const pipeline::M2Model* getModelData(uint32_t modelId) const;
     void setActiveGeosets(uint32_t instanceId, const std::unordered_set<uint16_t>& geosets);
     void setGroupTextureOverride(uint32_t instanceId, uint16_t geosetGroup, VkTexture* texture);

src/core/application.cpp

@@ -2794,6 +2794,16 @@ void Application::setupUICallbacks() {
         }
     });
 
+    // Ghost state callback — make player semi-transparent when in spirit form
+    gameHandler->setGhostStateCallback([this](bool isGhost) {
+        if (!renderer) return;
+        auto* cr = renderer->getCharacterRenderer();
+        if (!cr) return;
+        uint32_t charInstId = renderer->getCharacterInstanceId();
+        if (charInstId == 0) return;
+        cr->setInstanceOpacity(charInstId, isGhost ? 0.5f : 1.0f);
+    });
+
     // Stand state animation callback — map server stand state to M2 animation on player
     // and sync camera sit flag so movement is blocked while sitting
     gameHandler->setStandStateCallback([this](uint8_t standState) {

src/game/game_handler.cpp

@@ -7749,6 +7749,7 @@ void GameHandler::handleUpdateObject(network::Packet& packet) {
                             releasedSpirit_ = true;
                             playerDead_ = true;
                             LOG_INFO("Player logged in as ghost (PLAYER_FLAGS)");
+                            if (ghostStateCallback_) ghostStateCallback_(true);
                         }
                     }
                     // Determine hostility from faction template for online creatures
@@ -8212,12 +8213,14 @@ void GameHandler::handleUpdateObject(network::Packet& packet) {
                                 if (!wasGhost && nowGhost) {
                                     releasedSpirit_ = true;
                                     LOG_INFO("Player entered ghost form (PLAYER_FLAGS)");
+                                    if (ghostStateCallback_) ghostStateCallback_(true);
                                 } else if (wasGhost && !nowGhost) {
                                     releasedSpirit_ = false;
                                     playerDead_ = false;
                                     repopPending_ = false;
                                     resurrectPending_ = false;
                                     LOG_INFO("Player resurrected (PLAYER_FLAGS ghost cleared)");
+                                    if (ghostStateCallback_) ghostStateCallback_(false);
                                 }
                             }
                         }

src/rendering/character_renderer.cpp

@@ -2876,6 +2876,15 @@ void CharacterRenderer::startFadeIn(uint32_t instanceId, float durationSeconds)
     it->second.fadeInDuration = durationSeconds;
 }
 
+void CharacterRenderer::setInstanceOpacity(uint32_t instanceId, float opacity) {
+    auto it = instances.find(instanceId);
+    if (it != instances.end()) {
+        it->second.opacity = std::clamp(opacity, 0.0f, 1.0f);
+        // Cancel any fade-in in progress to avoid overwriting the new opacity
+        it->second.fadeInDuration = 0.0f;
+    }
+}
+
 void CharacterRenderer::setActiveGeosets(uint32_t instanceId, const std::unordered_set<uint16_t>& geosets) {
     auto it = instances.find(instanceId);
     if (it != instances.end()) {