```

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/components/game/SeatPlayerCard.vue

@@ -0,0 +1,23 @@
+<script setup lang="ts">
+import type { SeatPlayerCardModel } from './seat-player-card'
+
+defineProps<{
+  seatClass: string
+  player: SeatPlayerCardModel
+}>()
+</script>
+
+<template>
+  <article
+    class="player-badge"
+    :class="[seatClass, { 'is-turn': player.isTurn, offline: !player.isOnline }]"
+  >
+    <div class="avatar-card">{{ player.avatar }}</div>
+    <div class="player-meta">
+      <p>{{ player.name }}</p>
+      <strong>{{ player.money }}</strong>
+    </div>
+    <span v-if="player.dealer" class="dealer-mark">庄</span>
+    <span class="missing-mark">{{ player.missingSuitLabel }}</span>
+  </article>
+</template>