feat: Implement public access for tenant content

- Add TenantOptionalAuth middleware to allow access to public content without requiring authentication.
- Introduce ListPublicPublished and PublicDetail methods in the content service to retrieve publicly accessible content.
- Create tenant_public HTTP routes for listing and showing public content, including preview and main asset retrieval.
- Enhance content tests to cover scenarios for public content access and permissions.
- Update specifications to reflect the new public content access features and rules.

backend/app/services/tenant_join.go

@@ -9,7 +9,7 @@ import (
 
 	"quyun/v2/app/errorx"
 	"quyun/v2/app/http/tenant/dto"
-	tenantjoindto "quyun/v2/app/http/tenantjoin/dto"
+	tenant_join_dto "quyun/v2/app/http/tenant_join/dto"
 	"quyun/v2/app/requests"
 	"quyun/v2/database/models"
 	"quyun/v2/pkg/consts"
@@ -297,7 +297,7 @@ func (t *tenant) JoinByInvite(ctx context.Context, tenantID, userID int64, invit
 }
 
 // CreateJoinRequest 用户提交加入租户申请（无邀请码场景）。
-func (t *tenant) CreateJoinRequest(ctx context.Context, tenantID, userID int64, form *tenantjoindto.JoinRequestCreateForm) (*models.TenantJoinRequest, error) {
+func (t *tenant) CreateJoinRequest(ctx context.Context, tenantID, userID int64, form *tenant_join_dto.JoinRequestCreateForm) (*models.TenantJoinRequest, error) {
 	if tenantID <= 0 || userID <= 0 {
 		return nil, errorx.ErrInvalidParameter.WithMsg("invalid tenant_id/user_id")
 	}