Initial commit: Gitea Project Management System

Features:
- Complete project management system with Epic/Story/Task hierarchy
- Vue.js 3 + Element Plus frontend with kanban board
- Go backend with Gin framework and GORM
- OAuth2 integration with Gitea
- Docker containerization with MySQL
- RESTful API for project, task, and user management
- JWT authentication and authorization
- Responsive web interface with dashboard

internal/models/sprint.go

@@ -0,0 +1,139 @@
+package models
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+type Sprint struct {
+	ID          uint      `json:"id" gorm:"primaryKey"`
+	ProjectID   uint      `json:"project_id"`
+	Name        string    `json:"name" gorm:"not null"`
+	Description string    `json:"description"`
+	Status      string    `json:"status" gorm:"default:'planning'"`
+	StartDate   *time.Time `json:"start_date"`
+	EndDate     *time.Time `json:"end_date"`
+	Goal        string    `json:"goal"`
+	Project     Project   `json:"project" gorm:"foreignKey:ProjectID"`
+	Stories     []Story   `json:"stories" gorm:"foreignKey:SprintID"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+type SprintStatus string
+
+const (
+	SprintStatusPlanning  SprintStatus = "planning"
+	SprintStatusActive    SprintStatus = "active"
+	SprintStatusCompleted SprintStatus = "completed"
+)
+
+func (s *Sprint) BeforeCreate(tx *gorm.DB) error {
+	return nil
+}
+
+func (s *Sprint) GetVelocity() (int, error) {
+	var totalStoryPoints int
+	err := DB.Model(&Story{}).
+		Where("sprint_id = ? AND status = 'done'", s.ID).
+		Select("COALESCE(SUM(story_points), 0)").
+		Scan(&totalStoryPoints).Error
+	return totalStoryPoints, err
+}
+
+func (s *Sprint) GetBurndownData() ([]map[string]interface{}, error) {
+	var stories []Story
+	err := DB.Where("sprint_id = ?", s.ID).Find(&stories).Error
+	if err != nil {
+		return nil, err
+	}
+
+	var burndownData []map[string]interface{}
+	
+	// Calculate total story points
+	totalPoints := 0
+	for _, story := range stories {
+		if story.StoryPoints != nil {
+			totalPoints += *story.StoryPoints
+		}
+	}
+
+	// This is a simplified version - in a real implementation,
+	// you'd track daily progress
+	burndownData = append(burndownData, map[string]interface{}{
+		"date":      s.StartDate,
+		"remaining": totalPoints,
+		"ideal":     totalPoints,
+	})
+
+	if s.EndDate != nil {
+		burndownData = append(burndownData, map[string]interface{}{
+			"date":      s.EndDate,
+			"remaining": 0,
+			"ideal":     0,
+		})
+	}
+
+	return burndownData, nil
+}
+
+func CreateSprint(sprint *Sprint) error {
+	return DB.Create(sprint).Error
+}
+
+func GetSprintByID(id uint) (*Sprint, error) {
+	var sprint Sprint
+	err := DB.Preload("Project").Preload("Stories.Assignee").
+		First(&sprint, id).Error
+	return &sprint, err
+}
+
+func GetSprintsByProject(projectID uint) ([]Sprint, error) {
+	var sprints []Sprint
+	err := DB.Where("project_id = ?", projectID).
+		Preload("Stories").
+		Find(&sprints).Error
+	return sprints, err
+}
+
+func GetActiveSprintByProject(projectID uint) (*Sprint, error) {
+	var sprint Sprint
+	err := DB.Where("project_id = ? AND status = 'active'", projectID).
+		Preload("Stories.Assignee").
+		First(&sprint).Error
+	return &sprint, err
+}
+
+func UpdateSprint(sprint *Sprint) error {
+	return DB.Save(sprint).Error
+}
+
+func DeleteSprint(id uint) error {
+	return DB.Delete(&Sprint{}, id).Error
+}
+
+func ListSprints(offset, limit int, filters map[string]interface{}) ([]Sprint, int64, error) {
+	var sprints []Sprint
+	var total int64
+
+	query := DB.Model(&Sprint{})
+	
+	for key, value := range filters {
+		switch key {
+		case "project_id":
+			query = query.Where("project_id = ?", value)
+		case "status":
+			query = query.Where("status = ?", value)
+		}
+	}
+
+	err := query.Count(&total).Error
+	if err != nil {
+		return nil, 0, err
+	}
+
+	err = query.Preload("Project").
+		Offset(offset).Limit(limit).Find(&sprints).Error
+	return sprints, total, err
+}