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/services/api.ts

@@ -1,4 +1,4 @@
-import { get, post, put, del, getList } from './request'
+import { get, post, put, del, getList, postForm } from './request'
 
 export interface LoginParams { username: string; password: string }
 export interface LoginResult { token: string; user_id: number; tenant_id: number; nickname: string; role: string }
@@ -107,6 +107,38 @@ export const addSessionNote = (id: number, content: string) => post<SessionEvent
 export const sendSessionMessage = (id: number, content: string, type: 'text' | 'image' = 'text') => post<Message>(`/sessions/${id}/messages`, { content, type })
 export const getAvailableAgents = () => get<AvailableAgent[]>('/agents/available')
 
+export interface UploadImageResult {
+  url: string
+  thumb_url: string
+  content_type: string
+  width: number
+  height: number
+  size: number
+}
+
+/** 客服端上传图片 → 返回对象存储 URL */
+export const uploadImage = (file: File) => {
+  const form = new FormData()
+  form.append('file', file)
+  return postForm<UploadImageResult>('/uploads', form)
+}
+
+/** 访客端上传图片 */
+export const uploadWidgetImage = async (file: File, sessionId: number, visitorToken: string) => {
+  const form = new FormData()
+  form.append('file', file)
+  form.append('session_id', String(sessionId))
+  form.append('visitor_token', visitorToken)
+  const res = await fetch('/api/widget/upload', {
+    method: 'POST',
+    headers: { 'X-Visitor-Token': visitorToken },
+    body: form,
+  })
+  const json = await res.json()
+  if (json.code !== 0) throw new Error(json.message || '上传失败')
+  return json as { code: number; data: UploadImageResult }
+}
+
 // Customers
 export const getCustomers = (params?: { search?: string; status?: string; source?: string; page?: number; pageSize?: number }) => {
   const search = new URLSearchParams()