Initial commit: FunStat MCP Server Go implementation

- Telegram integration for customer statistics
- MCP server implementation with rate limiting
- Cache system for performance optimization
- Multi-language support
- RESTful API endpoints

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

internal/telegram/messages.go

@@ -0,0 +1,63 @@
+package telegram
+
+import (
+	"fmt"
+
+	"github.com/gotd/td/tg"
+)
+
+func extractMessages(resp tg.MessagesMessagesClass) ([]*tg.Message, error) {
+	switch v := resp.(type) {
+	case *tg.MessagesMessages:
+		return filterMessages(v.Messages), nil
+	case *tg.MessagesMessagesSlice:
+		return filterMessages(v.Messages), nil
+	case *tg.MessagesChannelMessages:
+		return filterMessages(v.Messages), nil
+	case *tg.MessagesMessagesNotModified:
+		return nil, fmt.Errorf("messages not modified")
+	default:
+		return nil, fmt.Errorf("unsupported response type %T", resp)
+	}
+}
+
+func filterMessages(values []tg.MessageClass) []*tg.Message {
+	result := make([]*tg.Message, 0, len(values))
+	for _, m := range values {
+		if msg, ok := m.(*tg.Message); ok {
+			result = append(result, msg)
+		}
+	}
+	return result
+}
+
+func extractMessageByID(resp tg.MessagesMessagesClass, id int) (*tg.Message, error) {
+	messages, err := extractMessages(resp)
+	if err != nil {
+		return nil, err
+	}
+	for _, msg := range messages {
+		if msg.ID == id {
+			return msg, nil
+		}
+	}
+	return nil, fmt.Errorf("message %d not found", id)
+}
+
+func isFromBot(msg *tg.Message, botID int64) bool {
+	if msg == nil || msg.Out {
+		return false
+	}
+
+	if peer, ok := msg.GetPeerID().(*tg.PeerUser); ok && peer.UserID == botID {
+		return true
+	}
+
+	if fromClass, ok := msg.GetFromID(); ok {
+		if from, ok := fromClass.(*tg.PeerUser); ok && from.UserID == botID {
+			return true
+		}
+	}
+
+	return false
+}