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/customer_access_test.go

@@ -0,0 +1,42 @@
+package contract
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestBindCustomerAccessProofToExactPersistedMessage(t *testing.T) {
+	ctx := WithCustomerAccessProof(context.Background(), CustomerAccessProof{
+		SessionID: "opaque-session", TargetType: "device", TargetID: 27,
+		ExpiresAt: time.Now().Add(time.Minute),
+	})
+	ctx = BindCustomerAccessProofToMessage(ctx, 101, 202, " request-303 ")
+	proof, ok := CustomerAccessProofFromContext(ctx)
+	if !ok {
+		t.Fatal("bound proof was not returned")
+	}
+	if proof.ConversationID != 101 || proof.MessageID != 202 || proof.RequestID != "request-303" {
+		t.Fatalf("proof was not bound to exact request message: %#v", proof)
+	}
+}
+
+func TestCustomerAccessProofRejectsExpiredOrUnscopedClaims(t *testing.T) {
+	for name, proof := range map[string]CustomerAccessProof{
+		"expired": {
+			SessionID: "opaque-session", TargetType: "card", TargetID: 1,
+			ExpiresAt: time.Now().Add(-time.Second),
+		},
+		"unsupported_target": {
+			SessionID: "opaque-session", TargetType: "guest", TargetID: 1,
+			ExpiresAt: time.Now().Add(time.Minute),
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			ctx := WithCustomerAccessProof(context.Background(), proof)
+			if _, ok := CustomerAccessProofFromContext(ctx); ok {
+				t.Fatalf("invalid proof was accepted: %#v", proof)
+			}
+		})
+	}
+}