fix(mobile): replace emoji glyphs with uni-icons and flex centering app-wide

- ChatComposer panel contract: callers now pass uni-icons type names
  (image/sound/list/help/checkmark) instead of emoji
- voice playback buttons: sound icon + pulse animation, no more 🔊/◼ chars
- practice recent list: rare symbols ⌕⌁◉ (tofu risk) -> wallet/gear/chatbubble
- sop resource icon ▶/文 -> 视/文 character badges
- back arrows: 22 char-based ← -> uni-icons back across 21 pages
- line-height centering -> flex in 8 spots (back buttons, media-remove,
  turn-voice capsule, option-marker, text-button, play-question)

mobile-uni/src/pages/user/sop/index.vue

@@ -52,7 +52,13 @@
                   :class="{ playing: isVoicePlaying(msg) }"
                   @click="playVoice(msg)"
                 >
-                  <text class="voice-icon">{{ isVoicePlaying(msg) ? '◼' : '🔊' }}</text>
+                  <uni-icons
+                    class="voice-icon"
+                    :class="{ playing: isVoicePlaying(msg) }"
+                    type="sound"
+                    size="17"
+                    :color="isVoicePlaying(msg) ? '#e70014' : '#5a6270'"
+                  />
                   <text class="voice-duration">{{ voiceLabel(msg) }}</text>
                 </view>
                 <view v-if="msg.unread" class="voice-dot" />
@@ -139,7 +145,7 @@
                   :class="{ video: resource.type === 'VIDEO' }"
                   @click="openKnowledgeResource(resource)"
                 >
-                  <view class="resource-icon">{{ resource.type === 'VIDEO' ? '▶' : '文' }}</view>
+                  <view class="resource-icon">{{ resource.type === 'VIDEO' ? '视' : '文' }}</view>
                   <view class="resource-copy">
                     <text class="resource-title">{{ resource.title }}</text>
                     <text class="resource-meta">
@@ -1989,16 +1995,19 @@ onUnload(() => {
 }
 
 .media-remove {
+  display: flex;
   width: 32px;
   min-width: 32px;
   height: 32px;
   min-height: 32px;
+  align-items: center;
+  justify-content: center;
   padding: 0;
   border-radius: 50%;
   background: #ffffff;
   color: var(--employee-muted);
   font-size: 21px;
-  line-height: 32px;
+  line-height: 1;
 }
 
 .answer-title-row {
@@ -2467,10 +2476,18 @@ onUnload(() => {
 }
 
 .voice-icon {
-  font-size: 15px;
   line-height: 1;
 }
 
+.voice-icon.playing {
+  animation: voice-icon-pulse 1s ease-in-out infinite;
+}
+
+@keyframes voice-icon-pulse {
+  0%, 100% { opacity: 1; }
+  50% { opacity: 0.4; }
+}
+
 .voice-duration {
   color: #232a33;
   font-size: 15px;