feat(qml): task #14a 图片生成 tab 核心闭环（无参考图）

ImageGenTab.qml wiring 改造：
- 加状态 properties: refImages / currentTaskId / lastResultPath / statusText / statusColor
- TextArea 取 placeholder，删硬编码 "风景画" 占位
- 模式/宽高比/尺寸 三个 ComboBox 给 id，submit() 时取 currentText
- 操作行 "生成图片" PrimaryButton onClicked → tab.submit()
  - submit 内部空 prompt 阻断 + 重复点击防护 + 调 imageGen.submitTask
  - 任务进行中按钮文字 "生成中…"，结束自动恢复
- Connections 监听 imageGen 4 个信号：
  - taskSubmitted → "● 已提交"
  - taskProgress → "● 正在生成…"
  - taskCompleted → 拿 resultPath 更新 lastResultPath，"● 已完成"
  - taskFailed → "● <error>"，红色
- 预览 Rectangle 内嵌 Image (file:/// + lastResultPath, cache:false 强制重读)
  - 无图片时显示占位文字，有图时直接展示

未做（task #14b/c/d 后续 commit）：
- 添加图片 / 粘贴图片 按钮（QFileDialog + QClipboard，桥要补 Slot）
-  收藏 + 删除 saved_prompts 持久化
- 下载图片 按钮 / 双击预览打开系统查看器

视觉验证：QML_AUTO_LOGIN=1 启动主窗口，所有控件渲染无回归。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

@@ -5,6 +5,68 @@ import "components"
 import "." as App
 
 Item {
+    id: tab
+
+    // ===== 状态 =====
+    property var refImages: []           // list[str] 参考图本地路径，task #14b 接上传/粘贴/拖拽
+    property string currentTaskId: ""    // 当前进行中的任务 id（同一时刻最多一个）
+    property string lastResultPath: ""   // 最近一次 taskCompleted 的图片路径
+    property string statusText: "● 就绪"
+    property color statusColor: App.Theme.success
+
+    // ===== 桥层信号 =====
+    Connections {
+        target: imageGen
+
+        function onTaskSubmitted(taskId) {
+            tab.currentTaskId = taskId
+            tab.statusText = "● 已提交"
+            tab.statusColor = App.Theme.accent
+        }
+
+        function onTaskProgress(taskId, progress, msg) {
+            if (taskId !== tab.currentTaskId) return
+            tab.statusText = "● " + (msg || "生成中…")
+            tab.statusColor = App.Theme.accent
+        }
+
+        function onTaskCompleted(taskId, resultPath, prompt, model) {
+            if (taskId !== tab.currentTaskId) return
+            tab.lastResultPath = resultPath
+            tab.currentTaskId = ""
+            tab.statusText = "● 已完成"
+            tab.statusColor = App.Theme.success
+        }
+
+        function onTaskFailed(taskId, error) {
+            if (taskId !== tab.currentTaskId) return
+            tab.currentTaskId = ""
+            tab.statusText = "● " + (error || "失败")
+            tab.statusColor = App.Theme.danger
+        }
+    }
+
+    function submit() {
+        if (tab.currentTaskId !== "") return  // busy
+        if (promptArea.text.trim().length === 0) {
+            tab.statusText = "● 请输入提示词"
+            tab.statusColor = App.Theme.danger
+            return
+        }
+        try {
+            imageGen.submitTask(
+                promptArea.text.trim(),
+                tab.refImages,
+                aspectCombo.currentText,
+                sizeCombo.currentText,
+                modeCombo.currentText
+            )
+        } catch (e) {
+            tab.statusText = "● " + e
+            tab.statusColor = App.Theme.danger
+        }
+    }
+
     ColumnLayout {
         anchors.fill: parent
         anchors.margins: App.Theme.space5
@@ -32,10 +94,10 @@ Item {
 
                 RowLayout {
                     spacing: App.Theme.space2
-                    SecondaryButton { text: "添加图片" }
-                    SecondaryButton { text: "📋 粘贴图片" }
+                    SecondaryButton { text: "添加图片"; enabled: false }
+                    SecondaryButton { text: "📋 粘贴图片"; enabled: false }
                     Label {
-                        text: "已选择 0 张"
+                        text: "已选择 " + tab.refImages.length + " 张"
                         font.family: App.Theme.fontFamily
                         font.pointSize: App.Theme.fontSm
                         color: App.Theme.textSecondary
@@ -93,7 +155,7 @@ Item {
 
                     RowLayout {
                         spacing: App.Theme.space2
-                        SecondaryButton { text: "⭐ 收藏" }
+                        SecondaryButton { text: "⭐ 收藏"; enabled: false }
                         Label {
                             text: "快速选择:"
                             font.family: App.Theme.fontFamily
@@ -101,17 +163,21 @@ Item {
                             color: App.Theme.textSecondary
                         }
                         ThemedComboBox {
+                            id: quickPromptCombo
                             Layout.fillWidth: true
                             model: ["主石换成闪耀的祖母绿", "改成玫瑰金材质", "增加更多碎钻"]
+                            onActivated: promptArea.text = currentText
                         }
-                        SecondaryButton { text: "删除" }
+                        SecondaryButton { text: "删除"; enabled: false }
                     }
 
                     ScrollView {
                         Layout.fillWidth: true
                         Layout.fillHeight: true
                         TextArea {
-                            text: "一幅美丽的风景画，有山有湖，日落时分"
+                            id: promptArea
+                            text: ""
+                            placeholderText: "描述你想生成的图片…"
                             font.family: App.Theme.fontFamily
                             font.pointSize: App.Theme.fontBase
                             color: App.Theme.textPrimary
@@ -142,21 +208,37 @@ Item {
                         font.pointSize: App.Theme.fontLg
                     }
 
-                    Repeater {
-                        model: [
-                            { caption: "生成模式", options: ["极速模式", "慢速模式"] },
-                            { caption: "宽高比", options: ["1:1", "2:3", "3:2", "16:9", "9:16", "4:3", "3:4"] },
-                            { caption: "图片尺寸", options: ["1K", "2K", "4K"] }
-                        ]
-                        delegate: ColumnLayout {
+                    ColumnLayout {
+                        spacing: 4
+                        Layout.fillWidth: true
+                        CaptionLabel { text: "生成模式"; font.pointSize: App.Theme.fontBase }
+                        ThemedComboBox {
+                            id: modeCombo
+                            Layout.fillWidth: true
+                            model: ["极速模式", "慢速模式"]
+                        }
+                    }
+
+                    ColumnLayout {
                         spacing: 4
                         Layout.fillWidth: true
-                            CaptionLabel { text: modelData.caption; font.pointSize: App.Theme.fontBase }
+                        CaptionLabel { text: "宽高比"; font.pointSize: App.Theme.fontBase }
                         ThemedComboBox {
+                            id: aspectCombo
                             Layout.fillWidth: true
-                                model: modelData.options
+                            model: ["1:1", "2:3", "3:2", "16:9", "9:16", "4:3", "3:4"]
                         }
                     }
+
+                    ColumnLayout {
+                        spacing: 4
+                        Layout.fillWidth: true
+                        CaptionLabel { text: "图片尺寸"; font.pointSize: App.Theme.fontBase }
+                        ThemedComboBox {
+                            id: sizeCombo
+                            Layout.fillWidth: true
+                            model: ["1K", "2K", "4K"]
+                        }
                     }
 
                     Item { Layout.fillHeight: true }
@@ -170,16 +252,19 @@ Item {
             Layout.fillWidth: true
 
             PrimaryButton {
-                text: "生成图片"
+                text: tab.currentTaskId !== "" ? "生成中…" : "生成图片"
+                enabled: tab.currentTaskId === ""
+                onClicked: tab.submit()
             }
             SecondaryButton {
                 text: "下载图片"
+                enabled: false
             }
             Label {
-                text: "● 就绪"
+                text: tab.statusText
                 font.family: App.Theme.fontFamily
                 font.pointSize: App.Theme.fontSm
-                color: App.Theme.success
+                color: tab.statusColor
             }
             Item { Layout.fillWidth: true }
         }
@@ -206,9 +291,22 @@ Item {
                     color: App.Theme.bgSubtle
                     radius: App.Theme.radiusMd
 
+                    Image {
+                        id: previewImage
+                        anchors.fill: parent
+                        anchors.margins: App.Theme.space3
+                        source: tab.lastResultPath ? "file:///" + tab.lastResultPath : ""
+                        fillMode: Image.PreserveAspectFit
+                        smooth: true
+                        asynchronous: true
+                        cache: false  // 同路径下次生成会被覆盖，强制重读
+                        visible: tab.lastResultPath !== ""
+                    }
+
                     Column {
                         anchors.centerIn: parent
                         spacing: 4
+                        visible: tab.lastResultPath === ""
 
                         Text {
                             anchors.horizontalCenter: parent.horizontalCenter