chore(game-ui): extract GameScreen domains into DialogManager + SettingsPanel

- Add `DialogManager` + `SettingsPanel` UI modules
- Refactor `GameScreen` to delegate dialogs and settings to new domains
- Update CMakeLists.txt to include new sources
- Include header/source files:
  - dialog_manager.hpp
  - settings_panel.hpp
  - dialog_manager.cpp
  - settings_panel.cpp
  - game_screen.cpp
- Keep `GameScreen` surface behavior while decoupling feature responsibilities

include/ui/dialog_manager.hpp

@@ -0,0 +1,71 @@
+#pragma once
+
+#include <imgui.h>
+#include <string>
+#include <cstdint>
+
+namespace wowee {
+namespace game { class GameHandler; }
+namespace ui {
+
+class ChatPanel;
+class InventoryScreen;
+
+/**
+ * Dialog / popup overlay manager
+ *
+ * Owns all yes/no popup rendering:
+ *   group invite, duel request, duel countdown, loot roll, trade request,
+ *   trade window, summon request, shared quest, item text, guild invite,
+ *   ready check, BG invite, BF manager invite, LFG proposal, LFG role check,
+ *   resurrect, talent wipe confirm, pet unlearn confirm.
+ */
+class DialogManager {
+public:
+    DialogManager() = default;
+
+    /// Render "early" dialogs (group invite through LFG role check)
+    /// called in render() before guild roster / social frame
+    void renderDialogs(game::GameHandler& gameHandler,
+                       InventoryScreen& inventoryScreen,
+                       ChatPanel& chatPanel);
+
+    /// Render "late" dialogs (resurrect, talent wipe, pet unlearn)
+    /// called in render() after reclaim corpse button
+    void renderLateDialogs(game::GameHandler& gameHandler);
+
+private:
+    // Common ImGui window flags for popup dialogs
+    static constexpr ImGuiWindowFlags kDialogFlags =
+        ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize;
+
+    // ---- LFG role state ----
+    uint8_t lfgRoles_ = 0x08;  // default: DPS (0x02=tank, 0x04=healer, 0x08=dps)
+
+    // ---- Individual dialog renderers ----
+    void renderGroupInvitePopup(game::GameHandler& gameHandler);
+    void renderDuelRequestPopup(game::GameHandler& gameHandler);
+    void renderDuelCountdown(game::GameHandler& gameHandler);
+    void renderItemTextWindow(game::GameHandler& gameHandler);
+    void renderSharedQuestPopup(game::GameHandler& gameHandler);
+    void renderSummonRequestPopup(game::GameHandler& gameHandler);
+    void renderTradeRequestPopup(game::GameHandler& gameHandler);
+    void renderTradeWindow(game::GameHandler& gameHandler,
+                           InventoryScreen& inventoryScreen,
+                           ChatPanel& chatPanel);
+    void renderLootRollPopup(game::GameHandler& gameHandler,
+                             InventoryScreen& inventoryScreen,
+                             ChatPanel& chatPanel);
+    void renderGuildInvitePopup(game::GameHandler& gameHandler);
+    void renderReadyCheckPopup(game::GameHandler& gameHandler);
+    void renderBgInvitePopup(game::GameHandler& gameHandler);
+    void renderBfMgrInvitePopup(game::GameHandler& gameHandler);
+    void renderLfgProposalPopup(game::GameHandler& gameHandler);
+    void renderLfgRoleCheckPopup(game::GameHandler& gameHandler);
+    void renderResurrectDialog(game::GameHandler& gameHandler);
+    void renderTalentWipeConfirmDialog(game::GameHandler& gameHandler);
+    void renderPetUnlearnConfirmDialog(game::GameHandler& gameHandler);
+};
+
+} // namespace ui
+} // namespace wowee