[Feature]: Stop writing uploads to the web root  #60

What type of issue is this?

• Bug report
• Feature request

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of the reqifviewer
• I have searched open and closed issues to ensure it has not already been reported

Description

IndexPage saves each upload to wwwroot/uploads/<guid> before parsing it. The files are not served today because they have no extension, but the folder is the web root, and files are left behind when the app stops before cleaning up. Related: #46 raised the upload size limit.

Acceptance criteria

• Uploaded files are read into memory (or the system temp folder) instead of wwwroot/uploads; nothing is left behind after loading, cancelling or an error.
• The upload size limit and supported extensions (.reqif, .reqifz, .zip, case-insensitive) are shown before uploading.

Steps to Reproduce

Load requirements-and-objects.reqifz or ProR_Traceability-Template-v1.0.reqif (reqifviewer.Tests/TestData) and look at the pages mentioned above.

System Configuration

• reqifviewer version: 6.1.0 (development, with [Refactor] Blazor Blueprint app shell and Blazor Web App hosting #56)
• Environment (Operating system, version and so on): Windows 11, Chrome
• .NET Framework version: .NET 10
• Additional information: Plan item F-04 of the viewer improvement plan. Size: S.