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.

app.wxss

@@ -153,6 +153,29 @@ button[disabled]:active {
   font-weight: 700;
 }
 
+.status-copy {
+  flex: 1;
+  min-width: 0;
+}
+
+.status-request-id,
+.request-id-row {
+  display: flex;
+  align-items: flex-start;
+  gap: 16rpx;
+  margin-top: 10rpx;
+  color: #6e6e73;
+  font-size: 22rpx;
+  line-height: 1.4;
+}
+
+.status-request-id > text:first-child,
+.request-id-row > text:first-child {
+  flex: 1;
+  min-width: 0;
+  word-break: break-all;
+}
+
 .loading-state {
   padding: 70rpx 32rpx;
   color: #6e6e73;