feat: 收件箱功能新增按回车查看详情面板

- 添加邮件详情面板显示（主题、发件人、收件人、抄送、账户、时间、正文）
- 优化邮件列表卡片样式，增加选中高亮效果
- 窗口宽度 >= 80 时启用双面板布局，左侧列表右侧详情
- 简化依赖包，从 charm.land 使用统一导入路径
- 删除未使用的 golangci/goreleaser 配置文件

inbox.go

@@ -3,13 +3,32 @@ package main
 import (
 	"fmt"
 
-	"github.com/charmbracelet/bubbletea"
+	"charm.land/bubbletea/v2"
 	"github.com/charmbracelet/pop/inbox"
 )
 
 func runInbox(days int) error {
 	m := inbox.NewInboxModel()
 	m.SetLoading(true)
+	m.SetDetailFetcher(func(accountID string, uid uint32) (*inbox.EmailDetail, error) {
+		detail, err := FetchEmailDetailByUID(accountID, uid)
+		if err != nil || detail == nil {
+			return nil, err
+		}
+		return &inbox.EmailDetail{
+			UID:       detail.UID,
+			From:      detail.From,
+			FromName:  detail.FromName,
+			To:        detail.To,
+			Cc:        detail.Cc,
+			Subject:   detail.Subject,
+			Date:      detail.Date,
+			TextBody:  detail.TextBody,
+			HTMLBody:  detail.HTMLBody,
+			Account:   detail.Account,
+			AccountID: detail.AccountID,
+		}, nil
+	})
 
 	emails, err := FetchAllUnreadEmails(days)
 	if err != nil {