Add a codebase/repository WebCrawler and build an crawled documentation index in SCP

The idea is to find and crawl blogs and presentations and other sources and add them to the SCP documentation index for a repo/group/organization - all info/documentation/++ in one place, always updated and close to the source

No files, tests, or entry points are named. Start by reviewing the SourceCodePortal repository structure and how its documentation index currently works, then clarify the sources, crawling scope, update behavior, and repository or organization targets; done should mean a working crawler and an updated index covering the agreed sources.

Written by the indexing model from the issue text.