DNF90 服务端与启动器完整源码（含 GM 工具功能增强）

服务端（Go）：
- GM 塞背包/带属性装备发放：在线角色推送 op14 增量物品行，背包实时刷新，无需回角色选择界面
- GM 改金币/改等级：去掉在线拒绝，落库后推送 op14 钱包/op37 等级状态，在线实时刷新
- 等级端点统一切换到新版 GMSetCharacterLevel（自带在线刷新）
- 无限/锁死疲劳模式 + 燃烧疲劳：每房间消耗 2 点、打怪与通关经验双倍
- 燃烧疲劳开关时给所有在线角色推送系统提示（op12 mode 0）
- 深渊史诗掉率：GM 全局倍率 + 城镇增益药剂窗口倍率，真实接入掉落结算

启动器（Python/JS）：
- 标题栏自绘、窗口 1204x717、禁止拖拽改大小、仅最小化/关闭
- GM 工具：疲劳与燃烧、深渊史诗掉率、拍卖行上架（单一定价对齐）
- 拍卖行上架前端对齐服务端单一价格语义，修复 400 报错

server/internal/modules/dnf/repository/mail_repository.go

@@ -0,0 +1,98 @@
+package repository
+
+import (
+	"context"
+	"strings"
+	"time"
+
+	"longheng.io/server/internal/platform/db"
+)
+
+// MailboxRepository persists the selected character's mailbox state.
+type MailboxRepository interface {
+	db.Store[MailboxRecord]
+}
+
+// MailboxRecord is the durable mailbox aggregate for one character.
+type MailboxRecord struct {
+	CharacterID string                `json:"character_id"`
+	Mails       map[string]MailRecord `json:"mails,omitempty"`
+	UpdatedAt   time.Time             `json:"updated_at,omitempty"`
+}
+
+// MailRecord is one server-owned mail. Attachments are claimed exactly once.
+type MailRecord struct {
+	MailID               string            `json:"mail_id"`
+	SenderCharacterID    string            `json:"sender_character_id,omitempty"`
+	SenderName           string            `json:"sender_name,omitempty"`
+	RecipientCharacterID string            `json:"recipient_character_id,omitempty"`
+	RecipientName        string            `json:"recipient_name,omitempty"`
+	Title                string            `json:"title,omitempty"`
+	Body                 string            `json:"body,omitempty"`
+	Gold                 int64             `json:"gold,omitempty"`
+	Attachments          []MailAttachment  `json:"attachments,omitempty"`
+	Read                 bool              `json:"read,omitempty"`
+	Claimed              bool              `json:"claimed,omitempty"`
+	Deleted              bool              `json:"deleted,omitempty"`
+	CreatedAt            time.Time         `json:"created_at,omitempty"`
+	ExpireAt             time.Time         `json:"expire_at,omitempty"`
+	Metadata             map[string]string `json:"metadata,omitempty"`
+}
+
+// MailAttachment is an inventory item attached to one mail.
+type MailAttachment struct {
+	ItemID   int64             `json:"item_id"`
+	Count    int64             `json:"count"`
+	Bind     bool              `json:"bind,omitempty"`
+	ExpireAt time.Time         `json:"expire_at,omitempty"`
+	RawEntry []byte            `json:"raw_entry,omitempty"`
+	Extra    map[string]string `json:"extra,omitempty"`
+}
+
+// MailboxField represents mailbox fields that support partial persistence.
+type MailboxField string
+
+const (
+	MailboxFieldMails MailboxField = "mails"
+)
+
+// SaveMailboxFields persists only selected mailbox fields when supported.
+func SaveMailboxFields(ctx context.Context, repo MailboxRepository, record MailboxRecord, fields ...MailboxField) error {
+	return db.SaveFields(ctx, repo, record, MailboxFields.Normalize, fields...)
+}
+
+// CloneMailbox deep-copies a mailbox aggregate.
+func CloneMailbox(record MailboxRecord) MailboxRecord {
+	record.Mails = cloneMailMap(record.Mails)
+	return record
+}
+
+func MailboxKey(record MailboxRecord) string {
+	return strings.TrimSpace(record.CharacterID)
+}
+
+func cloneMailMap(in map[string]MailRecord) map[string]MailRecord {
+	if len(in) == 0 {
+		return nil
+	}
+	out := make(map[string]MailRecord, len(in))
+	for key, value := range in {
+		value.Attachments = cloneMailAttachments(value.Attachments)
+		value.Metadata = cloneStringMap(value.Metadata)
+		out[key] = value
+	}
+	return out
+}
+
+func cloneMailAttachments(in []MailAttachment) []MailAttachment {
+	if len(in) == 0 {
+		return nil
+	}
+	out := make([]MailAttachment, len(in))
+	for idx, value := range in {
+		value.RawEntry = append([]byte(nil), value.RawEntry...)
+		value.Extra = cloneStringMap(value.Extra)
+		out[idx] = value
+	}
+	return out
+}