feat: integrate keybinding customization UI into Settings window

- Extended KeybindingManager enum with TOGGLE_GUILD_ROSTER (O) and
  TOGGLE_DUNGEON_FINDER (J) to replace hard-coded key checks
- Added Controls tab in Settings UI for rebinding all 10 customizable actions
- Implemented real-time key capture and binding with visual feedback
- Integrated keybinding persistence with main settings.cfg file
- Replaced hard-coded O key (Guild Roster) and I key (Dungeon Finder) checks
  with KeybindingManager::isActionPressed() calls
- Added Reset to Defaults button for restoring original keybindings

include/ui/keybinding_manager.hpp

@@ -23,6 +23,8 @@ public:
         TOGGLE_MINIMAP,
         TOGGLE_SETTINGS,
         TOGGLE_CHAT,
+        TOGGLE_GUILD_ROSTER,
+        TOGGLE_DUNGEON_FINDER,
         ACTION_COUNT
     };