refactor: 将客服后端重构为宿主可嵌入模块

- 注入数据库、运行时配置、统一响应、文件存储和平台 AI 能力，补充业务读写工具与客户快捷操作契约。

- 移除模块内重复的组织、客户、工单、标签、技能、旧工作流、MCP 和迁移实现，将身份权限与业务主体交由宿主管理。

- 使用 libSQL 重构向量存储，并完善图片消息、访客身份、排队调度、企业微信和支持聊天页面。

- 统一 HTTP、DTO 与 WebSocket 的 snake_case 协议，补齐模块初始化、业务动作和公共载荷等回归测试。

contract/business_read_tool.go

@@ -0,0 +1,31 @@
+package contract
+
+import "context"
+
+// BusinessReadContext identifies the customer bound to the current support
+// conversation. Host tools must use these trusted values instead of accepting
+// customer identifiers from model-generated arguments.
+type BusinessReadContext struct {
+	ConversationID     int64
+	CustomerType       string
+	CustomerID         int64
+	CustomerExternalID string
+	CustomerName       string
+	RequestMessageID   int64
+	RequestID          string
+	CheckPointID       string
+	AccessProof        *CustomerAccessProof
+}
+
+// BusinessReadTool lets the host expose a narrowly scoped, read-only business
+// query to AI Agent without coupling the customer-service module to host data.
+type BusinessReadTool struct {
+	Code          string
+	Description   string
+	CustomerTypes []string
+	InputSchema   map[string]any
+	// MatchIntent lets the host require a fresh read for messages whose answer
+	// must not rely on stale conversational text. It must be side-effect free.
+	MatchIntent func(string) bool
+	Execute     func(context.Context, BusinessReadContext, map[string]any) (any, error)
+}