实现 MinIO 对象存储图片流水线（可迁移 OSS）

- 新增 S3 兼容 Storage 抽象与 MinIO 实现，compose 启动 MinIO
- 上传接口：校验 → 缩放 → WebP → 主图/缩略图入库
- 消息图片 content 改为对象 URL，拒绝 base64
- 工作台/访客端改为先上传再发消息

web/src/pages/agent/Dashboard.tsx

@@ -10,6 +10,7 @@ import { useAuth } from '@/stores/auth'
 import {
   addSessionNote, claimSession, endSession, getAvailableAgents, getCustomers, getKnowledgeEntries,
   getSession, getSessions, markSessionRead, sendSessionMessage, transferSession, updateSessionPriority,
+  uploadImage,
   type AvailableAgent, type Customer, type KnowledgeEntry, type Message, type Session, type SessionEvent,
 } from '@/services/api'
 
@@ -111,7 +112,7 @@ const Dashboard = () => {
   const [knowledgeKeyword, setKnowledgeKeyword] = useState('')
   const [knowledgeEntries, setKnowledgeEntries] = useState<KnowledgeEntry[]>([])
   const [knowledgeLoading, setKnowledgeLoading] = useState(false)
-  const [imagePreview, setImagePreview] = useState<string | null>(null)
+  const [pendingImage, setPendingImage] = useState<{ file: File; preview: string } | null>(null)
   const [noteInput, setNoteInput] = useState('')
   const [savingNote, setSavingNote] = useState(false)
   const [customerHistory, setCustomerHistory] = useState<Session[]>([])
@@ -312,17 +313,34 @@ const Dashboard = () => {
 
   const handleImage = (file?: File) => {
     if (!file) return
-    if (!['image/jpeg', 'image/png', 'image/gif'].includes(file.type)) {
-      antMsg.error('仅支持 jpg、png、gif 图片')
+    const okTypes = ['image/jpeg', 'image/png', 'image/gif', 'image/webp']
+    if (!okTypes.includes(file.type)) {
+      antMsg.error('仅支持 jpg、png、gif、webp 图片')
       return
     }
-    if (file.size > 5 * 1024 * 1024) {
-      antMsg.error('图片不能超过 5 MB')
+    if (file.size > 10 * 1024 * 1024) {
+      antMsg.error('图片不能超过 10 MB')
       return
     }
-    const reader = new FileReader()
-    reader.onload = () => setImagePreview(String(reader.result))
-    reader.readAsDataURL(file)
+    if (pendingImage?.preview) URL.revokeObjectURL(pendingImage.preview)
+    setPendingImage({ file, preview: URL.createObjectURL(file) })
+  }
+
+  const confirmSendImage = async () => {
+    if (!pendingImage || !selectedId || !canOperate) return
+    setSending(true)
+    try {
+      const uploaded = await uploadImage(pendingImage.file)
+      await sendSessionMessage(selectedId, uploaded.data.url, 'image')
+      URL.revokeObjectURL(pendingImage.preview)
+      setPendingImage(null)
+      await loadDetail(selectedId)
+      await loadAll()
+    } catch (error) {
+      antMsg.error(error instanceof Error ? error.message : '图片发送失败')
+    } finally {
+      setSending(false)
+    }
   }
 
   const handleClaim = async (sessionID: number) => {
@@ -412,7 +430,7 @@ const Dashboard = () => {
       <input
         ref={fileInputRef}
         type="file"
-        accept="image/jpeg,image/png,image/gif"
+        accept="image/jpeg,image/png,image/gif,image/webp"
         className="hidden"
         onChange={event => { handleImage(event.target.files?.[0]); event.currentTarget.value = '' }}
       />
@@ -1006,15 +1024,19 @@ const Dashboard = () => {
       </Modal>
       <Modal
         title="图片预览"
-        open={Boolean(imagePreview)}
-        onCancel={() => setImagePreview(null)}
-        onOk={() => { if (imagePreview) sendMessage(imagePreview, 'image'); setImagePreview(null) }}
-        okText="发送"
+        open={Boolean(pendingImage)}
+        onCancel={() => {
+          if (pendingImage?.preview) URL.revokeObjectURL(pendingImage.preview)
+          setPendingImage(null)
+        }}
+        onOk={confirmSendImage}
+        okText="上传并发送"
         okButtonProps={{ loading: sending }}
       >
         <div className="flex justify-center">
-          <img src={imagePreview || ''} alt="待发送图片预览" className="max-h-[420px] max-w-full rounded-lg" />
+          <img src={pendingImage?.preview || ''} alt="待发送图片预览" className="max-h-[420px] max-w-full rounded-lg" />
         </div>
+        <p className="text-xs text-neutral-400 text-center mt-3 mb-0">将自动压缩并转为 WebP 后上传</p>
       </Modal>
       <Modal title="知识库与快捷回复" open={knowledgeOpen} onCancel={() => setKnowledgeOpen(false)} footer={null} width={640}>
         <Input