feat: 更新后端skill服务

- 更新 skill_handler.go handler层
- 更新 skill.go model层
- 更新 skill_repo.go repository层
- 更新 skill_service.go service层
- 更新 main.go 入口文件

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/internal/service/skill_service.go

@@ -77,8 +77,8 @@ func (s *SkillService) InitSkills() error {
 
 	var totalCount int
 
-	// 扫描 system skills: account/admin/skills
-	systemSkillsPath := filepath.Join(projectRoot, "account", "admin", "skills")
+	// 扫描 system skills: core/agents/skills/system
+	systemSkillsPath := filepath.Join(projectRoot, "core", "agents", "skills", "system")
 	if _, err := os.Stat(systemSkillsPath); err == nil {
 		systemSkills, err := s.scanSkillsDirectory(systemSkillsPath, "system")
 		if err == nil && len(systemSkills) > 0 {
@@ -88,22 +88,14 @@ func (s *SkillService) InitSkills() error {
 		}
 	}
 
-	// 扫描 user skills: account/{username}/skills (除了 admin)
-	accountPath := filepath.Join(projectRoot, "account")
-	entries, err := os.ReadDir(accountPath)
-	if err == nil {
-		for _, entry := range entries {
-			if !entry.IsDir() || entry.Name() == "admin" {
-				continue
-			}
-			userSkillsPath := filepath.Join(accountPath, entry.Name(), "skills")
-			if _, err := os.Stat(userSkillsPath); err == nil {
-				userSkills, err := s.scanSkillsDirectory(userSkillsPath, "user")
-				if err == nil && len(userSkills) > 0 {
-					s.skillRepo.UpsertBatch(userSkills)
-					totalCount += len(userSkills)
-				}
-			}
+	// 扫描 user skills: core/agents/skills/user
+	userSkillsPath := filepath.Join(projectRoot, "core", "agents", "skills", "user")
+	if _, err := os.Stat(userSkillsPath); err == nil {
+		userSkills, err := s.scanSkillsDirectory(userSkillsPath, "user")
+		if err == nil && len(userSkills) > 0 {
+			s.skillRepo.DeleteByType("user")
+			s.skillRepo.UpsertBatch(userSkills)
+			totalCount += len(userSkills)
 		}
 	}