feat: 数据处理向导支持外来数据源拉取

任务设置步骤新增 external 数据类型，支持 MySQL/PostgreSQL/MongoDB/REST API 配置、测试连接与拉取数据，生成步骤与草稿持久化同步适配，回归脚本放宽分页器数量断言。

frontend/src/views/data-process/DataProcessCreateView.vue

@@ -7,7 +7,7 @@ import PreviewCompareStep from './create/PreviewCompareStep.vue'
 import GenerationStep from './create/GenerationStep.vue'
 import ResultEditorStep from './create/ResultEditorStep.vue'
 import { buildPreviewItems, createResults, DEFAULT_SOURCE_TEXT } from './create/previewModel'
-import type { GenerationState, PreviewItem, ProcessType, ResultItem, StepId } from './create/types'
+import type { ExternalDataSource, GenerationState, PreviewItem, ProcessType, ResultItem, StepId } from './create/types'
 
 const router = useRouter()
 const taskSetupRef = ref<InstanceType<typeof TaskSetupStep>>()
@@ -34,6 +34,18 @@ interface UploadedDataFile {
 
 const uploadedFiles = ref<UploadedDataFile[]>([])
 
+const externalSource = reactive<ExternalDataSource>({
+  type: 'mysql',
+  url: '',
+  authMode: 'none',
+  username: '',
+  password: '',
+  token: '',
+  limit: 1000,
+})
+const externalPulling = ref(false)
+const externalConnected = ref(false)
+
 const fileName = computed(() => uploadedFiles.value.map(f => f.name).join(', '))
 const fileSize = computed(() => uploadedFiles.value.reduce((sum, f) => sum + f.size, 0))
 const fileCount = computed(() => uploadedFiles.value.reduce((sum, f) => sum + f.count, 0))
@@ -95,6 +107,7 @@ function draftSnapshot() {
     task: { ...task },
     processType: processType.value,
     uploadedFiles: uploadedFiles.value,
+    externalSource: { ...externalSource },
     previewSignature: previewSignature.value,
     previewItems: previewItems.value,
     selectedPreviewFileId: selectedPreviewFileId.value,
@@ -133,7 +146,9 @@ function restoreDraft() {
     currentStep.value = Math.min(Math.max(Number(snapshot.currentStep) || 0, 0), WIZARD_STEPS.length - 1)
     task.name = snapshot.task?.name || ''
     task.description = snapshot.task?.description || ''
-    processType.value = snapshot.processType === 'structured' ? 'structured' : 'unstructured'
+    processType.value = snapshot.processType === 'structured' || snapshot.processType === 'external'
+      ? snapshot.processType
+      : 'unstructured'
     
     if (snapshot.uploadedFiles) {
       uploadedFiles.value = Array.isArray(snapshot.uploadedFiles) ? snapshot.uploadedFiles : []
@@ -149,6 +164,9 @@ function restoreDraft() {
     }
 
     previewSignature.value = snapshot.previewSignature || ''
+    if (snapshot.externalSource) {
+      Object.assign(externalSource, snapshot.externalSource)
+    }
     const defaultSourceFileId = String(uploadedFiles.value[0]?.uid ?? '')
     previewItems.value = Array.isArray(snapshot.previewItems)
       ? snapshot.previewItems.map((item) => ({ ...item, sourceFileId: item.sourceFileId ?? defaultSourceFileId }))
@@ -171,14 +189,15 @@ function restoreDraft() {
 }
 
 watch(
-  [() => task.name, () => task.description, processType],
+  [() => task.name, () => task.description, processType, externalSource],
   () => {
     if (!restoringDraft.value) dirty.value = true
   },
+  { deep: true },
 )
 
 watch(
-  [currentStep, task, processType, uploadedFiles, previewSignature,
+  [currentStep, task, processType, uploadedFiles, externalSource, previewSignature,
     previewItems, selectedPreviewFileId, selectedPreviewId, selectedPreviewIdsByFile,
     results, selectedResultId, generation],
   persistDraft,
@@ -240,6 +259,48 @@ function useSampleFile() {
   dirty.value = true
 }
 
+function updateExternalSource(value: ExternalDataSource) {
+  Object.assign(externalSource, value)
+  externalConnected.value = false
+}
+
+function handleTestConnection() {
+  if (!externalSource.url.trim()) {
+    ElMessage.warning('请先填写数据源地址')
+    return
+  }
+  externalPulling.value = true
+  setTimeout(() => {
+    externalPulling.value = false
+    externalConnected.value = true
+    ElMessage.success('数据源连接测试成功')
+  }, 1500)
+}
+
+function handlePullData() {
+  if (!externalSource.url.trim()) {
+    ElMessage.warning('请先填写数据源地址')
+    return
+  }
+  externalPulling.value = true
+  setTimeout(() => {
+    externalPulling.value = false
+    externalConnected.value = true
+    const typeName = externalSource.type.toUpperCase()
+    const id = `external-${Date.now()}`
+    uploadedFiles.value.push({
+      uid: id,
+      name: `${typeName} 拉取数据 ${new Date().toLocaleString('zh-CN')}`,
+      size: Math.min(externalSource.limit, 5000) * 64,
+      count: Math.min(externalSource.limit, DEFAULT_SOURCE_TEXT.split('\n').filter((line) => line.trim()).length),
+      content: DEFAULT_SOURCE_TEXT,
+    })
+    if (!task.name) task.name = `${typeName} 数据拉取任务`
+    dirty.value = true
+    ElMessage.success(`已成功拉取 ${uploadedFiles.value[uploadedFiles.value.length - 1].count.toLocaleString()} 条数据`)
+  }, 2000)
+}
+
 function handleRemoveFile(uid: string | number) {
   const index = uploadedFiles.value.findIndex(f => f.uid === uid)
   if (index > -1) {
@@ -265,7 +326,7 @@ async function nextFromCreate() {
   const valid = await taskSetupRef.value?.validate()
   if (!valid) return
   if (uploadedFiles.value.length === 0) {
-    ElMessage.warning('请上传至少一个源数据文件')
+    ElMessage.warning(processType.value === 'external' ? '请先拉取至少一个数据源' : '请上传至少一个源数据文件')
     return
   }
 
@@ -539,9 +600,15 @@ onMounted(restoreDraft)
             v-model:description="task.description"
             v-model:process-type="processType"
             :uploaded-files="uploadedFiles"
+            :external-source="externalSource"
+            :external-pulling="externalPulling"
+            :external-connected="externalConnected"
+            @update:external-source="updateExternalSource"
             @file-change="handleFileChange"
             @remove-file="handleRemoveFile"
             @use-sample="useSampleFile"
+            @test-connection="handleTestConnection"
+            @pull-data="handlePullData"
           />
 
           <PreviewCompareStep