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。

internal/ai/application/runtime/application_service_test.go

@@ -1,9 +1,13 @@
 package runtime
 
 import (
+	"context"
+	"net/http"
 	"strings"
 	"testing"
 
+	"code.tczkiot.com/wlw/ai-agent/contract"
+	"code.tczkiot.com/wlw/ai-agent/internal/ai"
 	"code.tczkiot.com/wlw/ai-agent/internal/models"
 	"code.tczkiot.com/wlw/ai-agent/internal/pkg/enums"
 
@@ -12,6 +16,48 @@ import (
 	"gorm.io/gorm"
 )
 
+type runtimePlatformAIProvider struct{}
+
+func (runtimePlatformAIProvider) ModelSource(context.Context) (string, error) {
+	return contract.ModelSourcePlatform, nil
+}
+
+type runtimeVisionOnlyPlatformAIProvider struct{}
+
+func (runtimeVisionOnlyPlatformAIProvider) ModelSource(context.Context) (string, error) {
+	return contract.ModelSourcePlatform, nil
+}
+
+func (runtimeVisionOnlyPlatformAIProvider) Config(context.Context) (*contract.PlatformAIConfig, error) {
+	return &contract.PlatformAIConfig{
+		APIKey:        "platform-managed",
+		BaseURL:       "https://platform.example/v1",
+		ChatEnabled:   false,
+		ChatModel:     "qwen-plus",
+		VisionEnabled: true,
+		VisionModel:   "qwen3-vl-plus",
+	}, nil
+}
+
+func (runtimeVisionOnlyPlatformAIProvider) Status(context.Context) (*contract.PlatformAIStatus, error) {
+	return &contract.PlatformAIStatus{VisionEnabled: true, VisionModel: "qwen3-vl-plus"}, nil
+}
+
+func (runtimePlatformAIProvider) Config(context.Context) (*contract.PlatformAIConfig, error) {
+	return &contract.PlatformAIConfig{
+		APIKey:        "license-signed",
+		BaseURL:       "https://platform.example/v1",
+		ModelName:     "platform-default",
+		TimeoutMS:     30000,
+		MaxRetryCount: 1,
+		HTTPClient:    &http.Client{},
+	}, nil
+}
+
+func (runtimePlatformAIProvider) Status(context.Context) (*contract.PlatformAIStatus, error) {
+	return &contract.PlatformAIStatus{Enabled: true}, nil
+}
+
 func TestAgentApplicationServiceLoadsConsistentPersistedRequest(t *testing.T) {
 	db, err := gorm.Open(sqlite.Open("file:"+strings.ReplaceAll(t.Name(), "/", "_")+"?mode=memory&cache=shared"), &gorm.Config{})
 	if err != nil {
@@ -52,3 +98,32 @@ func TestAgentApplicationServiceRejectsMismatchedMessage(t *testing.T) {
 		t.Fatal("expected invalid identifiers error")
 	}
 }
+
+func TestResolveRuntimeAIConfigUsesPlatformWithoutCustomConfig(t *testing.T) {
+	ai.SetPlatformAIProvider(runtimePlatformAIProvider{})
+	t.Cleanup(func() { ai.SetPlatformAIProvider(nil) })
+
+	config, err := ResolveRuntimeAIConfig(context.Background(), 0)
+	if err != nil {
+		t.Fatalf("ResolveRuntimeAIConfig() error = %v", err)
+	}
+	if !config.Platform || config.ModelName != "platform-default" || config.APIKey != "license-signed" {
+		t.Fatalf("ResolveRuntimeAIConfig() = %+v", config)
+	}
+}
+
+func TestResolveRuntimeAIConfigForImageUsesVisionWhenChatIsDisabled(t *testing.T) {
+	ai.SetPlatformAIProvider(runtimeVisionOnlyPlatformAIProvider{})
+	t.Cleanup(func() { ai.SetPlatformAIProvider(nil) })
+
+	config, err := ResolveRuntimeAIConfigForMessage(context.Background(), 0, enums.IMMessageTypeImage)
+	if err != nil {
+		t.Fatalf("ResolveRuntimeAIConfigForMessage(image) error = %v", err)
+	}
+	if config.ModelName != "qwen3-vl-plus" || !config.VisionEnabled {
+		t.Fatalf("ResolveRuntimeAIConfigForMessage(image) = %+v", config)
+	}
+	if _, err := ResolveRuntimeAIConfigForMessage(context.Background(), 0, enums.IMMessageTypeText); err == nil || !strings.Contains(err.Error(), "chat model is not enabled") {
+		t.Fatalf("text must still require chat capability, got %v", err)
+	}
+}