feat(observability): add structured application logging

Emit correlated JSON logs from the API and FunASR services, propagate request IDs to the client, and configure bounded opt-in Docker logging.

Document the host-wide Grafana/Loki query workflow and keep observability deployment ownership outside the application repository.

pages/profile/index.wxml

@@ -13,6 +13,10 @@
       <text class="connection-dot connection-{{connectionTone}}"></text>
       <text class="connection-text">{{connectionText}}</text>
     </view>
+    <view wx:if="{{connectionRequestId}}" class="request-id-row">
+      <text>请求编号：{{connectionRequestId}}</text>
+      <text class="status-action" data-request-id="{{connectionRequestId}}" bindtap="copyRequestId">复制</text>
+    </view>
     <button class="primary-button check-button" loading="{{testing}}" disabled="{{testing}}" bindtap="saveAndCheck">保存并检测</button>
   </view>
 
@@ -22,6 +26,10 @@
       <text class="connection-dot connection-{{authTone}}"></text>
       <text class="connection-text">{{authText}}</text>
     </view>
+    <view wx:if="{{authRequestId}}" class="request-id-row">
+      <text>请求编号：{{authRequestId}}</text>
+      <text class="status-action" data-request-id="{{authRequestId}}" bindtap="copyRequestId">复制</text>
+    </view>
     <text wx:if="{{authUserId}}" class="identity-value">{{authUserId}}</text>
   </view>
 </view>