feat(material): add material handling and routing functionality

- Introduced MaterialHandler for managing learning materials and subjects.
- Updated router to include routes for public and admin material management.
- Enhanced database initialization with material subject and file models.
- Implemented seeding logic for material subjects and files.
- Updated wire generation to include MaterialHandler and related services.

internal/model/init.go

@@ -159,6 +159,10 @@ func autoMigrate(db *gorm.DB) error {
 		&Role{},
 		&UserRole{},
 		&CasbinRule{},
+
+		// 学习资料相关
+		&MaterialSubject{},
+		&MaterialFile{},
 	)
 	if err != nil {
 		return err
@@ -184,6 +188,11 @@ func autoMigrate(db *gorm.DB) error {
 		return fmt.Errorf("failed to seed channels: %w", err)
 	}
 
+	// 初始化学习资料学科种子数据
+	if err := seedMaterialSubjects(db); err != nil {
+		return fmt.Errorf("failed to seed material subjects: %w", err)
+	}
+
 	return nil
 }
 
@@ -321,8 +330,18 @@ func seedPermissions(db *gorm.DB) error {
 	return nil
 }
 
-// seedChannels 初始化频道种子数据（按 slug 幂等）
+// seedChannels 初始化频道种子数据（仅在表为空时）
 func seedChannels(db *gorm.DB) error {
+	// 检查是否已有频道数据
+	var count int64
+	if err := db.Model(&Channel{}).Count(&count).Error; err != nil {
+		return err
+	}
+	if count > 0 {
+		zap.L().Info("Channels already exist, skipping seed", zap.Int64("count", count))
+		return nil
+	}
+
 	defaultChannels := []Channel{
 		{Name: "跳蚤市场", Slug: "market", Description: "二手交易与闲置发布", SortOrder: 10, IsActive: true},
 		{Name: "课程交流", Slug: "courses", Description: "课程资料、选课与学习讨论", SortOrder: 20, IsActive: true},
@@ -331,33 +350,45 @@ func seedChannels(db *gorm.DB) error {
 		{Name: "保研出国", Slug: "graduate-abroad", Description: "保研、留学申请与经验分享", SortOrder: 50, IsActive: true},
 	}
 
-	for _, item := range defaultChannels {
-		var existing Channel
-		err := db.Where("slug = ?", item.Slug).First(&existing).Error
-		if err == nil {
-			updates := map[string]any{
-				"name":        item.Name,
-				"description": item.Description,
-				"sort_order":  item.SortOrder,
-				"is_active":   item.IsActive,
-			}
-			if uerr := db.Model(&existing).Updates(updates).Error; uerr != nil {
-				return uerr
-			}
-			continue
-		}
-		if err != nil && err != gorm.ErrRecordNotFound {
-			return err
-		}
-		if cerr := db.Create(&item).Error; cerr != nil {
-			return cerr
-		}
+	if err := db.Create(&defaultChannels).Error; err != nil {
+		return err
 	}
 
 	zap.L().Info("Seeded channels successfully", zap.Int("count", len(defaultChannels)))
 	return nil
 }
 
+// seedMaterialSubjects 初始化学习资料学科种子数据（仅在表为空时）
+func seedMaterialSubjects(db *gorm.DB) error {
+	// 检查是否已有数据
+	var count int64
+	if err := db.Model(&MaterialSubject{}).Count(&count).Error; err != nil {
+		return err
+	}
+	if count > 0 {
+		zap.L().Info("Material subjects already exist, skipping seed", zap.Int64("count", count))
+		return nil
+	}
+
+	defaultSubjects := []MaterialSubject{
+		{Name: "数学", Icon: "calculator-variant", Color: "#FF6B6B", Description: "高等数学、线性代数、概率论等", SortOrder: 10, IsActive: true},
+		{Name: "英语", Icon: "translate", Color: "#4ECDC4", Description: "四六级、考研英语、托福雅思等", SortOrder: 20, IsActive: true},
+		{Name: "物理", Icon: "atom", Color: "#45B7D1", Description: "大学物理、电磁学、力学等", SortOrder: 30, IsActive: true},
+		{Name: "化学", Icon: "flask", Color: "#96CEB4", Description: "有机化学、无机化学、分析化学等", SortOrder: 40, IsActive: true},
+		{Name: "计算机", Icon: "laptop", Color: "#FFEAA7", Description: "数据结构、算法、操作系统等", SortOrder: 50, IsActive: true},
+		{Name: "经济管理", Icon: "chart-line", Color: "#DDA0DD", Description: "微观经济学、宏观经济学、管理学等", SortOrder: 60, IsActive: true},
+		{Name: "法学", Icon: "scale-balance", Color: "#F39C12", Description: "民法、刑法、宪法等", SortOrder: 70, IsActive: true},
+		{Name: "语文文学", Icon: "book-open-page-variant", Color: "#3498DB", Description: "古代文学、现代文学、写作等", SortOrder: 80, IsActive: true},
+	}
+
+	if err := db.Create(&defaultSubjects).Error; err != nil {
+		return err
+	}
+
+	zap.L().Info("Seeded material subjects successfully", zap.Int("count", len(defaultSubjects)))
+	return nil
+}
+
 // CloseDB 关闭数据库连接
 func CloseDB(db *gorm.DB) {
 	if sqlDB, err := db.DB(); err == nil {