physics: implement HOVER movement flag physics in CameraController

When the server sets MovementFlags::HOVER (SMSG_MOVE_SET_HOVER), the
player now floats 4 yards above the nearest ground surface instead of
standing on it. Uses the existing floor-snap path with a HOVER_HEIGHT
offset applied to the snap target.

- game_handler.hpp: add isHovering() accessor (reads HOVER flag from
  movementInfo.flags, which is already set by handleForceMoveFlagChange)
- camera_controller.hpp: add hoverActive_ field and setHoverActive()
- camera_controller.cpp: apply HOVER_HEIGHT = 4.0f offset at floor snap
- application.cpp: sync hover state each frame alongside other movement
  states (gravity, feather fall, water walk, flying)

include/game/game_handler.hpp

@@ -1173,6 +1173,9 @@ public:
                                  static_cast<uint32_t>(MovementFlags::FLYING);
         return (movementInfo.flags & flyMask) == flyMask;
     }
+    bool isHovering() const {
+        return (movementInfo.flags & static_cast<uint32_t>(MovementFlags::HOVER)) != 0;
+    }
     void dismount();
 
     // Taxi / Flight Paths