```

feat(game): add player cards and topbar styling for Chengdu Mahjong game

- Add new CSS classes for topbar layout including .topbar-left,
  .topbar-back-btn, .topbar-room-meta, .eyebrow, and .topbar-room-name
- Create dedicated player card components for each seat position
  (top, right, bottom, left)
- Refactor seatDecor computed property to use SeatPlayerCardModel
  interface with proper typing
- Replace inline player badge rendering with reusable player card
  components
- Update game header layout to use new topbar structure with
  back button and room metadata
- Adjust spacing and font sizes in game header elements
```

src/assets/styles/global.css

@@ -459,6 +459,39 @@ button:disabled {
   min-width: 0;
 }
 
+.topbar-left {
+  display: flex;
+  align-items: center;
+  gap: 14px;
+  min-width: 0;
+}
+
+.topbar-back-btn {
+  flex: 0 0 auto;
+  min-width: 108px;
+}
+
+.topbar-room-meta {
+  min-width: 0;
+}
+
+.eyebrow {
+  color: #f7e4b0;
+  font-size: 12px;
+  letter-spacing: 2px;
+  text-transform: uppercase;
+}
+
+.topbar-room-name {
+  margin-top: 4px;
+  color: #f6edd5;
+  font-size: 20px;
+  font-weight: 700;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
 .game-header h1 {
   font-size: 28px;
   font-weight: 800;
@@ -467,9 +500,9 @@ button:disabled {
 }
 
 .game-header .sub-title {
-  margin-top: 6px;
+  margin-top: 4px;
   color: #d7eadf;
-  font-size: 13px;
+  font-size: 12px;
   white-space: nowrap;
   overflow: hidden;
   text-overflow: ellipsis;
@@ -1195,6 +1228,10 @@ button:disabled {
     justify-items: stretch;
   }
 
+  .topbar-left {
+    flex-wrap: wrap;
+  }
+
   .topbar-center,
   .topbar-right {
     justify-content: flex-start;