feat: 定时发布系统 — Phase 5 完成

- Post ScheduledAt 字段
- Scheduler goroutine 每分钟扫描到期文章
- Create/Update 校验最短 30min 定时
- Approve 审核晚于定时则即时发布
- public 列表+空间页过滤未到期文章
- 写文章页 datetime-local 选择器（min=now+30min）
- AutoMigrate 追加新表

cmd/server/main.go

@@ -2,11 +2,14 @@ package main
 
 import (
 	"log"
+	"time"
 
 	"metazone.cc/mce/internal/common"
 	"metazone.cc/mce/internal/config"
 	"metazone.cc/mce/internal/model"
+	"metazone.cc/mce/internal/repository"
 	"metazone.cc/mce/internal/router"
+	"metazone.cc/mce/internal/scheduler"
 	"metazone.cc/mce/internal/theme"
 
 	"github.com/gin-gonic/gin"
@@ -27,7 +30,7 @@ func main() {
 	if err != nil {
 		log.Fatalf("连接数据库失败: %v", err)
 	}
-	if err := db.AutoMigrate(&model.User{}, &model.AuditSubmission{}, &model.SiteSetting{}, &model.Notification{}, &model.Post{}, &model.PostReadLog{}, &model.PostGuestReadLog{}, &model.UserCheckIn{}, &model.UserTask{}, &model.EnergyLog{}, &model.PostEnergizeLog{}, &model.DailyExpSummary{}, &model.Comment{}, &model.CommentMention{}, &model.CommunityFund{}, &model.FundLog{}, &model.PostLike{}, &model.PostDislike{}, &model.UserFollow{}, &model.DailyLikeSummary{}, &model.Folder{}, &model.FolderItem{}); err != nil {
+	if err := db.AutoMigrate(&model.User{}, &model.AuditSubmission{}, &model.SiteSetting{}, &model.Notification{}, &model.Post{}, &model.PostReadLog{}, &model.PostGuestReadLog{}, &model.UserCheckIn{}, &model.UserTask{}, &model.EnergyLog{}, &model.PostEnergizeLog{}, &model.DailyExpSummary{}, &model.Comment{}, &model.CommentMention{}, &model.CommunityFund{}, &model.FundLog{}, &model.PostLike{}, &model.PostDislike{}, &model.UserFollow{}, &model.DailyLikeSummary{}, &model.Folder{}, &model.FolderItem{}, &model.Announcement{}, &model.Category{}, &model.Tag{}, &model.PostTag{}); err != nil {
 		log.Fatalf("数据库迁移失败: %v", err)
 	}
 
@@ -98,6 +101,9 @@ func main() {
 	// 路由注册
 	router.Setup(r, db, cfg, siteSettings, redisClient)
 
+	// 定时发布调度器
+	scheduler.StartPublishScheduler(repository.NewPostRepo(db), 1*time.Minute)
+
 	// 启动
 	log.Printf("MetaZone.FAN 启动于 0.0.0.0:%s", cfg.Server.Port)
 	r.Run("0.0.0.0:" + cfg.Server.Port)