fix: same-slot reorder is a no-op; WM_DESTROY clears card drag state; fix card_meta.h ms-rounding comment

src/bank_panel.cpp

@@ -2922,6 +2922,7 @@ void onMouseMove(int x, int y) {
             g_panel.dropBankId.clear();
             g_panel.cardGesture = CardGesture::None;
             g_panel.dragTargetSlot = -1;
+            g_panel.dragPrimaryId.clear();
             invalidatePanel();
 
             // Empty path list -> nothing draggable (all stale/missing); do not start a drag.
@@ -3117,6 +3118,9 @@ WDL_DLGRET dlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
             stopAudition();
             g_panel.selection = Selection{};
             g_panel.dragArmed = g_panel.dragging = false;
+            g_panel.cardGesture = CardGesture::None;
+            g_panel.dragTargetSlot = -1;
+            g_panel.dragPrimaryId.clear();
             g_panel.hovered = Hover{};
             g_panel.tooltipShown = false;
             g_panel.hwnd = nullptr;