重构：把剩余 12 个顶层包全部迁到 internal/

继续之前的重构：把根目录残留的非数据/资源类子目录（agents、agenttool、ai、
autoreply、completion、conversation、llm、message、mqtpp、stream、
toolmanager、toolrouter）一并搬到 internal/ 下，并把全工程引用它们的
import 路径从 "meshtastic_mqtt_server/<x>" 重写为
"meshtastic_mqtt_server/internal/<x>"。

变更
- git mv 12 个顶层目录进 internal/，无函数体改动。
- 全工程 sed 把 import path 加上 internal/ 前缀，包括 main.go、
  internal/bot/bot_service.go、internal/store/bot_store.go 中对 mqtpp
  的引用，以及 ai 子系统内部 agents/agenttool/autoreply/conversation/
  llm/toolmanager/toolrouter 之间的相互引用。

验证
- go build ./... 通过；go test ./... 全部包通过。
- AI 自动回复链路（main → ai.NewService → autoreply.Service → botSender）
  保持不变，仅 import 路径调整。
- 根目录最终只剩 main.go / main_test.go / internal/ 加 go.mod / go.sum
  与数据资源目录（dist、doc、firmware、py、win、meshmap_frontend）。

Co-Authored-By: Claude <noreply@anthropic.com>

internal/completion/completion.go

@@ -0,0 +1,115 @@
+package completion
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"meshtastic_mqtt_server/internal/llm"
+	"meshtastic_mqtt_server/internal/message"
+
+	"github.com/volcengine/volcengine-go-sdk/service/arkruntime/model"
+)
+
+// ChatCompleter is a function that completes a chat
+type ChatCompleter func(ctx context.Context, profile *llm.Profile, req model.CreateChatCompletionRequest, timeout time.Duration) (model.ChatCompletionResponse, error)
+
+// CompleteChat completes a chat conversation
+func CompleteChat(ctx context.Context, profile *llm.Profile, req model.CreateChatCompletionRequest, timeout time.Duration) (model.ChatCompletionResponse, error) {
+	if profile == nil || profile.Client == nil {
+		return model.ChatCompletionResponse{}, fmt.Errorf("llm profile or client is nil")
+	}
+
+	// Use context with timeout if provided
+	if timeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, timeout)
+		defer cancel()
+	}
+
+	resp, err := profile.Client.CreateChatCompletion(ctx, req)
+	if err != nil {
+		return model.ChatCompletionResponse{}, fmt.Errorf("chat completion failed: %w", err)
+	}
+	return resp, nil
+}
+
+// CompleteText completes a text prompt using conversation messages
+// If systemPrompt is not empty, it will be added as the first message
+func CompleteText(ctx context.Context, profile *llm.Profile, systemPrompt string, messages []message.ChatMessage, maxTokens int) (string, error) {
+	if profile == nil || profile.Client == nil {
+		return "", fmt.Errorf("llm profile or client is nil")
+	}
+
+	arkMessages := make([]*model.ChatCompletionMessage, 0, len(messages)+1)
+
+	// Add system prompt if provided
+	if strings.TrimSpace(systemPrompt) != "" {
+		content := &model.ChatCompletionMessageContent{
+			StringValue: &systemPrompt,
+		}
+		arkMessages = append(arkMessages, &model.ChatCompletionMessage{
+			Role:    "system",
+			Content: content,
+		})
+	}
+
+	for _, msg := range messages {
+		content := &model.ChatCompletionMessageContent{
+			StringValue: &msg.Content,
+		}
+		arkMessages = append(arkMessages, &model.ChatCompletionMessage{
+			Role:    msg.Role,
+			Content: content,
+		})
+	}
+
+	req := model.CreateChatCompletionRequest{
+		Model:     profile.Config.Model,
+		Messages:  arkMessages,
+		MaxTokens: &maxTokens,
+	}
+
+	resp, err := profile.Client.CreateChatCompletion(ctx, req)
+	if err != nil {
+		return "", fmt.Errorf("text completion failed: %w", err)
+	}
+
+	if len(resp.Choices) == 0 {
+		return "", fmt.Errorf("no completion choices returned")
+	}
+
+	if resp.Choices[0].Message.Content != nil && resp.Choices[0].Message.Content.StringValue != nil {
+		return *resp.Choices[0].Message.Content.StringValue, nil
+	}
+	return "", nil
+}
+
+// CompleteTextWithArkMessages completes a text prompt using already converted Ark messages
+// This is used when messages have already been converted (e.g. after tool loop)
+func CompleteTextWithArkMessages(ctx context.Context, profile *llm.Profile, arkMessages []*model.ChatCompletionMessage, maxTokens int) (string, error) {
+	if profile == nil || profile.Client == nil {
+		return "", fmt.Errorf("llm profile or client is nil")
+	}
+
+	req := model.CreateChatCompletionRequest{
+		Model:     profile.Config.Model,
+		Messages:  arkMessages,
+		MaxTokens: &maxTokens,
+	}
+
+	resp, err := profile.Client.CreateChatCompletion(ctx, req)
+	if err != nil {
+		return "", fmt.Errorf("text completion failed: %w", err)
+	}
+
+	if len(resp.Choices) == 0 {
+		return "", fmt.Errorf("no completion choices returned")
+	}
+
+	if resp.Choices[0].Message.Content != nil && resp.Choices[0].Message.Content.StringValue != nil {
+		return *resp.Choices[0].Message.Content.StringValue, nil
+	}
+	return "", nil
+}