Build cross-platform Desktop app/software as an .exe, and one that could easily convert to mobile.

I need a cross-platform Desktop app/software as an .exe, and one that could easily convert to mobile. One I can fully customize myself and take full control of it, the ability to have full control and full ownership, with the ability to modify it by adding or removing docs on demand, (HTML Executable [login to view URL] allows me to do this). Keeping in mind that I need to have it in sellable form; that I will be selling it to customers. The .exe will house (over 2,000) Microsoft word docs, excel docs, some pdf's and the like. The documents are legal docs, mainly for court proceedings, some documents are for business-related activities such as partnership agreements. Other documents are for Employee and Human Resources, etc. I want the customer to be able to see the docs listed in a menu tree, click on the document and call it up within the program OR call it up outside the program and edit, save, print, etc.. It would behave like a library of documents or like a dashboard. Structured like folders/subfolders and contained within the subfolders are word, excel, pdf documents on a computer or laptop. The customer would be able to view from a menu tree, a directory/library of documents. An example of what the customer would see is here [login to view URL] The look and feel would be similar to that. I have a piece of software called HTML Executable from [login to view URL] that I'm trying to work with to accomplish this, but having trouble with the Table of Contents. I'm fumbling around with it really. So, rather than me trying to get this to work and accomplish what I need, can you do this and are you capable of creating a simple straight forward Exe software and mobile capable as well like this? and to where I can control the content, edit it by adding documents to the library, removing documents, etc. Thank you.