docs: Clean up obsolete pages, dead links, and unused files

[Jaredl-Dev]

Merge after #93.

Summary

• Removes 14 placeholder pages that only said "work in progress", plus their sidebar and Home entries.
• Removes 2.5 MB of files no page links to: two WorldBuilder PDFs and four INI/log dumps.
• Removes 15 dead navigation entries and 10 leftover MediaWiki [Category:] footers.
• Repairs broken links: the WND control pages now point at wnd_reference, and the 3dsmax, texturing, and DDS images use absolute raw URLs so they render on the published wiki.
• Adds the six DDS comparison images the page already referred to, and links the orphaned BIG file format page from the sidebar.