refactor: 优化前端聊天UI组件

- 优化MessageBubble消息气泡组件
- 优化MessageList消息列表组件

app-android/app/src/main/java/com/huaga/life_echo/ui/components/chat/MessageBubble.kt

@@ -8,6 +8,11 @@ import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.shadow
@@ -38,14 +43,14 @@ fun UserMessageBubble(
                 .shadow(2.dp, RoundedCornerShape(12.dp)),
             shape = RoundedCornerShape(12.dp),
             colors = CardDefaults.cardColors(
-                containerColor = LightPurple.copy(alpha = 0.2f)
+                containerColor = LightPurple  // 使用完整的紫色，不再使用透明度
             )
         ) {
             Text(
                 text = text,
                 modifier = Modifier.padding(12.dp),
                 fontSize = 14.sp,
-                color = MaterialTheme.colorScheme.onSurface,
+                color = Color.White,  // 使用白色文字，确保在紫色背景上清晰可见
                 lineHeight = 20.sp
             )
         }
@@ -87,3 +92,65 @@ fun AIMessageBubble(
         }
     }
 }
+
+/**
+ * 流式AI消息气泡（带光标闪烁效果）
+ */
+@Composable
+fun StreamingAIMessageBubble(
+    text: String,
+    modifier: Modifier = Modifier
+) {
+    var showCursor by remember { mutableStateOf(true) }
+    
+    // 光标闪烁动画
+    LaunchedEffect(Unit) {
+        while (true) {
+            showCursor = true
+            kotlinx.coroutines.delay(500)
+            showCursor = false
+            kotlinx.coroutines.delay(500)
+        }
+    }
+    
+    Row(
+        modifier = modifier
+            .fillMaxWidth()
+            .padding(horizontal = 16.dp, vertical = 8.dp),
+        horizontalArrangement = androidx.compose.foundation.layout.Arrangement.Start
+    ) {
+        Card(
+            modifier = Modifier
+                .weight(1f)
+                .shadow(2.dp, RoundedCornerShape(12.dp)),
+            shape = RoundedCornerShape(12.dp),
+            colors = CardDefaults.cardColors(
+                containerColor = MaterialTheme.colorScheme.surface
+            )
+        ) {
+            Row(
+                modifier = Modifier.padding(12.dp),
+                verticalAlignment = androidx.compose.ui.Alignment.CenterVertically
+            ) {
+                Text(
+                    text = text,
+                    fontSize = 14.sp,
+                    color = MaterialTheme.colorScheme.onSurface,
+                    lineHeight = 20.sp
+                )
+                // 光标闪烁效果
+                if (showCursor) {
+                    Text(
+                        text = "▊",
+                        fontSize = 14.sp,
+                        color = MaterialTheme.colorScheme.primary,
+                        fontWeight = FontWeight.Bold,
+                        modifier = Modifier.padding(start = 2.dp)
+                    )
+                } else {
+                    Spacer(modifier = Modifier.width(8.dp))
+                }
+            }
+        }
+    }
+}

app-android/app/src/main/java/com/huaga/life_echo/ui/components/chat/MessageList.kt

@@ -20,6 +20,7 @@ import androidx.compose.ui.unit.sp
 import com.huaga.life_echo.network.models.MessageDto
 import com.huaga.life_echo.ui.theme.LightPurple
 import com.huaga.life_echo.utils.TimeUtils
+import kotlinx.coroutines.delay
 
 /**
  * 消息列表组件
@@ -35,10 +36,18 @@ fun MessageList(
 ) {
     val listState = rememberLazyListState()
     
-    // 自动滚动到底部
-    LaunchedEffect(messages.size, isStreaming) {
-        if (messages.isNotEmpty() || isStreaming) {
-            listState.animateScrollToItem(messages.size)
+    // 自动滚动到底部 - 改进：流式输出时实时滚动
+    LaunchedEffect(messages.size, isStreaming, streamingText) {
+        val targetIndex = messages.size + if (isStreaming) 1 else 0
+        if (targetIndex > 0) {
+            // 流式输出时使用平滑滚动，其他情况使用动画滚动
+            if (isStreaming && streamingText.isNotEmpty()) {
+                // 流式输出时，每次文本更新都滚动到底部
+                kotlinx.coroutines.delay(50) // 短暂延迟确保内容已渲染
+                listState.animateScrollToItem(targetIndex)
+            } else {
+                listState.animateScrollToItem(targetIndex)
+            }
         }
     }
     
@@ -78,10 +87,10 @@ fun MessageList(
             lastDate = currentDate
         }
         
-        // 流式消息显示
+        // 流式消息显示 - 使用专门的流式消息气泡组件
         if (isStreaming) {
-            item {
-                AIMessageBubble(
+            item(key = "streaming_message") {
+                StreamingAIMessageBubble(
                     text = streamingText
                 )
             }