fix: 完善智能自动模式对话流程

修复内容：
1. 前端：检查用户最后一条消息是否有图片（而不是整个对话最后一条）
2. 前端：useEffect 依赖项添加 selectedModelId
3. 后端：错误回退时也生成友好消息
4. 后端：保存消息时添加完整的数据库字段
5. 分析器：增加颜色调整关键词匹配（改成X色、换成X色）

现在大模型（Qwen3 VL）会生成自然对话回复

Co-authored-by: Cursor <cursoragent@cursor.com>

app/(chat)/api/chat/route.ts

@@ -486,6 +486,8 @@ export async function POST(request: Request) {
         let bestModel = null;
         if (hasImage) {
           bestModel = allModels.find(m => m.model.supportsImageGen && !m.model.isSubModel);
+          // 🆕 回退时也生成一个友好消息
+          smartAutoFriendlyMessage = "好的，我来帮你处理这张图片~";
         }
         if (!bestModel) {
           bestModel = allModels.find(m => m.model.isDefault && !m.model.isSubModel);
@@ -1016,6 +1018,11 @@ export async function POST(request: Request) {
                     parts: [{ type: "text", text: smartAutoFriendlyMessage }],
                     attachments: [],
                     createdAt: new Date(),
+                    videoStorageStatus: null,
+                    temporaryVideoUrl: null,
+                    permanentVideoUrl: null,
+                    archivedAt: null,
+                    videoMetadata: null,
                   },
                 ],
               });
@@ -1235,6 +1242,11 @@ export async function POST(request: Request) {
                     parts: [{ type: "text", text: smartAutoFriendlyMessage }],
                     attachments: [],
                     createdAt: new Date(),
+                    videoStorageStatus: null,
+                    temporaryVideoUrl: null,
+                    permanentVideoUrl: null,
+                    archivedAt: null,
+                    videoMetadata: null,
                   },
                 ],
               });

components/messages.tsx

@@ -236,7 +236,7 @@ function PureMessages({
     else {
       setShowThinkingWithDelay(false);
     }
-  }, [status, messages, isGeminiModel, isQianwenVideoModel, isVolcanoVisionModel, isVideoModel, isAlibabaImageModel]);
+  }, [status, messages, isGeminiModel, isQianwenVideoModel, isVolcanoVisionModel, isVideoModel, isAlibabaImageModel, selectedModelId]);
 
   // 🆕 监听新消息添加，当用户发送带图片的消息或添加加载消息时，强制滚动到底部
   const prevMessagesLengthRef = useRef(messages.length);
@@ -365,9 +365,9 @@ function PureMessages({
             
             // 🆕 检查智能自动模式是否有图片（需要显示生图占位图）
             const isAutoMode = selectedModelId === "auto";
-            const userMessageHasImage = messages.length > 0 && 
+            // 🆕 找用户的最后一条消息（而不是整个对话的最后一条）
-              messages[messages.length - 1]?.role === "user" &&
+            const lastUserMsg = [...messages].reverse().find(m => m.role === "user");
-              messages[messages.length - 1]?.parts?.some((p: any) => p.type === "file" || p.type === "image");
+            const userMessageHasImage = lastUserMsg?.parts?.some((p: any) => p.type === "file" || p.type === "image");
             const showAutoModeImage = isAutoMode && userMessageHasImage;
             
             if (showVideo) return <QianwenVideoLoading />;

lib/ai/smart-analyzer.ts

@@ -312,13 +312,16 @@ export function fallbackKeywordAnalysis(
       };
     }
 
-    // 调色
+    // 调色/改颜色
-    if (/调色|调整颜色|亮度|对比度|饱和度|色调|曝光|滤镜/.test(lowerText)) {
+    if (/调色|调整颜色|亮度|对比度|饱和度|色调|曝光|滤镜|改成.*色|换成.*色|变成.*色|颜色改成|颜色换成|颜色变成/.test(lowerText)) {
+      // 提取目标颜色
+      const colorMatch = text.match(/(?:改成|换成|变成)(.+?)(?:色|$)/);
+      const color = colorMatch ? colorMatch[1].trim() + "色" : "";
       return {
         intent: "image_edit",
         subIntent: "color_adjust",
         confidence: 0.9,
-        conversationalReply: "收到，我来帮你调整图片色彩~",
+        conversationalReply: color ? `好的，我来帮你把颜色改成${color}~` : "收到，我来帮你调整图片色彩~",
       };
     }