Add separate draggable bag windows, fix dismount and player equipment

Bags are now individual draggable ImGui windows (backpack + each equipped
bag) with per-bag toggle from the bag bar. B key opens/closes all. A
settings toggle under Gameplay lets users switch back to the original
aggregate single-window mode. Window width adapts to bag item name length.

Fix dismount by clearing local mount state immediately (optimistic) instead
of waiting for server confirmation, and allow buff bar right-click dismount
regardless of the aura's buff flag.

Fix other players appearing naked by queuing them for auto-inspect when
the visible item field layout hasn't been detected yet.

include/ui/game_screen.hpp

@@ -82,6 +82,7 @@ private:
     int pendingUiOpacity = 65;
     bool pendingMinimapRotate = false;
     bool pendingMinimapSquare = false;
+    bool pendingSeparateBags = true;
 
     // UI element transparency (0.0 = fully transparent, 1.0 = fully opaque)
     float uiOpacity_ = 0.65f;