feat(qol & backup): add wave progress bar, hover collection, area explosion preview, hotkeys, auto-sync and json save export/import

game/js/systems/economy.js

@@ -559,6 +559,18 @@ window.EconomySystem = class EconomySystem {
 
       this.drawCardThumbnail(ctx, card.id, cx + cardW / 2, cardY + 28);
 
+      // Slot Hotkey Number Indicator (1..6)
+      if (i < 9) {
+        ctx.fillStyle = 'rgba(0, 0, 0, 0.45)';
+        ctx.beginPath();
+        ctx.roundRect(cx + 3, cardY + 3, 13, 13, 3);
+        ctx.fill();
+        ctx.fillStyle = '#ffffff';
+        ctx.font = 'bold 9px sans-serif';
+        ctx.textAlign = 'center';
+        ctx.fillText((i + 1).toString(), cx + 9.5, cardY + 13);
+      }
+
       if (this.workshop) {
         const lvl = this.workshop.getPlantLevel(card.id);
         if (lvl > 1) {
@@ -608,6 +620,16 @@ window.EconomySystem = class EconomySystem {
     ctx.lineWidth = isShovelSelected ? 3 : 2;
     ctx.stroke();
 
+    // Hotkey [S] badge on shovel
+    ctx.fillStyle = 'rgba(0, 0, 0, 0.45)';
+    ctx.beginPath();
+    ctx.roundRect(shovelX + 3, cardY + 3, 14, 13, 3);
+    ctx.fill();
+    ctx.fillStyle = '#ffffff';
+    ctx.font = 'bold 9px sans-serif';
+    ctx.textAlign = 'center';
+    ctx.fillText('S', shovelX + 10, cardY + 13);
+
     this.drawShovelGraphic(ctx, shovelX + 27, cardY + 36);
     ctx.fillStyle = '#37474f';
     ctx.font = 'bold 9px sans-serif';