Add character creation screen with race/class/appearance customization

Implements a full character creation UI integrated into the existing flow.
In single-player mode, auth screen now goes to character creation before
entering the world. In online mode, a "Create Character" button on the
character selection screen sends CMSG_CHAR_CREATE to the server. Includes
WoW 3.3.5a race/class combo validation and appearance range limits.

include/ui/character_create_screen.hpp

@@ -0,0 +1,42 @@
+#pragma once
+
+#include "game/character.hpp"
+#include "game/world_packets.hpp"
+#include <imgui.h>
+#include <string>
+#include <functional>
+#include <vector>
+
+namespace wowee {
+namespace game { class GameHandler; }
+
+namespace ui {
+
+class CharacterCreateScreen {
+public:
+    CharacterCreateScreen();
+
+    void render(game::GameHandler& gameHandler);
+    void setOnCreate(std::function<void(const game::CharCreateData&)> cb) { onCreate = std::move(cb); }
+    void setOnCancel(std::function<void()> cb) { onCancel = std::move(cb); }
+    void setStatus(const std::string& msg, bool isError = false);
+    void reset();
+
+private:
+    char nameBuffer[13] = {};  // WoW max name = 12 chars + null
+    int raceIndex = 0;
+    int classIndex = 0;
+    int genderIndex = 0;
+    int skin = 0, face = 0, hairStyle = 0, hairColor = 0, facialHair = 0;
+    std::string statusMessage;
+    bool statusIsError = false;
+
+    std::vector<game::Class> availableClasses;
+    void updateAvailableClasses();
+
+    std::function<void(const game::CharCreateData&)> onCreate;
+    std::function<void()> onCancel;
+};
+
+} // namespace ui
+} // namespace wowee

include/ui/character_screen.hpp

@@ -30,6 +30,8 @@ public:
         onCharacterSelected = callback;
     }
 
+    void setOnCreateCharacter(std::function<void()> cb) { onCreateCharacter = std::move(cb); }
+
     /**
      * Check if a character has been selected
      */
@@ -51,6 +53,7 @@ private:
 
     // Callbacks
     std::function<void(uint64_t)> onCharacterSelected;
+    std::function<void()> onCreateCharacter;
 
     /**
      * Update status message

include/ui/ui_manager.hpp

@@ -2,6 +2,7 @@
 
 #include "ui/auth_screen.hpp"
 #include "ui/realm_screen.hpp"
+#include "ui/character_create_screen.hpp"
 #include "ui/character_screen.hpp"
 #include "ui/game_screen.hpp"
 #include <memory>
@@ -64,6 +65,7 @@ public:
      */
     AuthScreen& getAuthScreen() { return *authScreen; }
     RealmScreen& getRealmScreen() { return *realmScreen; }
+    CharacterCreateScreen& getCharacterCreateScreen() { return *characterCreateScreen; }
     CharacterScreen& getCharacterScreen() { return *characterScreen; }
     GameScreen& getGameScreen() { return *gameScreen; }
 
@@ -73,6 +75,7 @@ private:
     // UI Screens
     std::unique_ptr<AuthScreen> authScreen;
     std::unique_ptr<RealmScreen> realmScreen;
+    std::unique_ptr<CharacterCreateScreen> characterCreateScreen;
     std::unique_ptr<CharacterScreen> characterScreen;
     std::unique_ptr<GameScreen> gameScreen;