feat: expand keybinding system with 4 new customizable actions

- Add World Map (W), Nameplates (V), Raid Frames (R), Quest Log (Q) to
  KeybindingManager enum with customizable default bindings
- Replace hard-coded V key check for nameplate toggle with
  KeybindingManager::isActionPressed() to support customization
- Update config file persistence to handle new bindings
- Infrastructure in place for implementing visibility toggles on other
  windows (World Map, Raid Frames, Quest Log) with future UI refactoring

include/ui/keybinding_manager.hpp

@@ -25,6 +25,10 @@ public:
         TOGGLE_CHAT,
         TOGGLE_GUILD_ROSTER,
         TOGGLE_DUNGEON_FINDER,
+        TOGGLE_WORLD_MAP,
+        TOGGLE_NAMEPLATES,
+        TOGGLE_RAID_FRAMES,
+        TOGGLE_QUEST_LOG,
         ACTION_COUNT
     };