[Feature]: Show pictures inline in rich text  #71

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

In the Subset026 sample the RichText cell says "Picture missing. No alternative text available." while the picture itself is shown separately under "Embedded Objects" at the bottom of the page: <xhtml:object> elements are not resolved to the attachment where they appear.

Acceptance criteria

• <xhtml:object> elements are rendered as images (data URIs via ReqIFLoaderService) where they appear in the text, with alt text; non-image attachments become download links.
• The separate "Embedded Objects" section goes away.

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 R-05 of the viewer improvement plan. Size: M. Depends on: [Bug]: Sanitize XHTML from ReqIF files before rendering it  #57.