refactor: remove Gorse integration and implement HotRank feature

- Removed Gorse-related configurations, handlers, and dependencies from the codebase.
- Introduced HotRank feature with configuration options for ranking posts based on recent activity.
- Updated application structure to support HotRank processing, including new caching mechanisms and database interactions.
- Cleaned up related DTOs and repository methods to reflect the removal of Gorse and the addition of HotRank functionality.

internal/model/post.go

@@ -43,7 +43,6 @@ type Post struct {
 	FavoritesCount int     `json:"favorites_count" gorm:"column:favorites_count;default:0"`
 	SharesCount    int     `json:"shares_count" gorm:"column:shares_count;default:0"`
 	ViewsCount     int     `json:"views_count" gorm:"column:views_count;default:0"`
-	HotScore       float64 `json:"hot_score" gorm:"column:hot_score;default:0;index:idx_posts_hot_score_created,priority:1"`
 
 	// 置顶/锁定
 	IsPinned   bool `json:"is_pinned" gorm:"default:false"`
@@ -58,7 +57,7 @@ type Post struct {
 	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
 
 	// 时间戳
-	CreatedAt time.Time `json:"created_at" gorm:"autoCreateTime;index:idx_posts_status_created,priority:2,sort:desc;index:idx_posts_user_status_created,priority:3,sort:desc;index:idx_posts_hot_score_created,priority:2,sort:desc"`
+	CreatedAt time.Time `json:"created_at" gorm:"autoCreateTime;index:idx_posts_status_created,priority:2,sort:desc;index:idx_posts_user_status_created,priority:3,sort:desc"`
 	UpdatedAt time.Time `json:"updated_at" gorm:"autoUpdateTime:false"`
 	// ContentEditedAt 仅在实际修改标题/正文/图片时更新，供前端展示「已编辑」；与统计类更新解耦
 	ContentEditedAt *time.Time `json:"content_edited_at,omitempty" gorm:"column:content_edited_at"`