fix(backend): license/info 返回 phase 字段，前端横幅/弹窗依赖此字段

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

backend/internal/handler/license.go

@@ -60,7 +60,15 @@ func (h *LicenseHandler) Info(c *gin.Context) {
 		c.JSON(http.StatusOK, gin.H{"data": nil})
 		return
 	}
-	c.JSON(http.StatusOK, gin.H{"data": lic})
+	phase := middleware.CalcLicensePhase(lic.ExpiresAt)
+	c.JSON(http.StatusOK, gin.H{"data": gin.H{
+		"id":          lic.ID,
+		"type":        lic.Type,
+		"is_active":   lic.IsActive,
+		"max_devices": lic.MaxDevices,
+		"expires_at":  lic.ExpiresAt,
+		"phase":       phase,
+	}})
 }
 
 // Deactivate POST /api/v1/license/deactivate