game/rendering: drive Walk(4) and swim state from movement flags

Add UnitMoveFlagsCallback fired on every MSG_MOVE_* with the raw
movement flags field. Application.cpp uses it to update swimming
and walking state from any packet, not just explicit START_SWIM/
STOP_SWIM opcodes — fixing cold-join cases where a player is already
swimming when we enter the world.

Per-frame animation sync now selects Walk(4) when the WALKING flag is
set, Run(5) otherwise, and Swim(42)/SwimIdle(41) when swimming.
UnitAnimHintCallback is simplified to jump (38=JumpMid) only.

include/core/application.hpp

@@ -188,7 +188,8 @@ private:
     std::unordered_map<uint64_t, uint32_t> creatureModelIds_;   // guid → loaded modelId
     std::unordered_map<uint64_t, glm::vec3> creatureRenderPosCache_; // guid -> last synced render position
     std::unordered_map<uint64_t, bool> creatureWasMoving_;       // guid -> previous-frame movement state
-    std::unordered_map<uint64_t, bool> creatureSwimmingState_;   // guid -> currently in swim mode
+    std::unordered_map<uint64_t, bool> creatureSwimmingState_;   // guid -> currently in swim mode (SWIMMING flag)
+    std::unordered_map<uint64_t, bool> creatureWalkingState_;    // guid -> walking (WALKING flag, selects Walk(4) vs Run(5))
     std::unordered_set<uint64_t> creatureWeaponsAttached_;       // guid set when NPC virtual weapons attached
     std::unordered_map<uint64_t, uint8_t> creatureWeaponAttachAttempts_; // guid -> attach attempts
     std::unordered_map<uint32_t, bool> modelIdIsWolfLike_;     // modelId → cached wolf/worg check

include/game/game_handler.hpp

@@ -637,10 +637,15 @@ public:
     using SpellCastAnimCallback = std::function<void(uint64_t guid, bool start, bool isChannel)>;
     void setSpellCastAnimCallback(SpellCastAnimCallback cb) { spellCastAnimCallback_ = std::move(cb); }
 
-    // Unit animation hint: signal jump (animId=38) or swim (animId=42) for other players/NPCs
+    // Unit animation hint: signal jump (animId=38) for other players/NPCs
     using UnitAnimHintCallback = std::function<void(uint64_t guid, uint32_t animId)>;
     void setUnitAnimHintCallback(UnitAnimHintCallback cb) { unitAnimHintCallback_ = std::move(cb); }
 
+    // Unit move-flags callback: fired on every MSG_MOVE_* for other players with the raw flags field.
+    // Drives Walk(4) vs Run(5) selection and swim state initialization from heartbeat packets.
+    using UnitMoveFlagsCallback = std::function<void(uint64_t guid, uint32_t moveFlags)>;
+    void setUnitMoveFlagsCallback(UnitMoveFlagsCallback cb) { unitMoveFlagsCallback_ = 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); }
@@ -2268,6 +2273,7 @@ private:
     MeleeSwingCallback meleeSwingCallback_;
     SpellCastAnimCallback spellCastAnimCallback_;
     UnitAnimHintCallback unitAnimHintCallback_;
+    UnitMoveFlagsCallback unitMoveFlagsCallback_;
     NpcSwingCallback npcSwingCallback_;
     NpcGreetingCallback npcGreetingCallback_;
     NpcFarewellCallback npcFarewellCallback_;