DoltHub: Repository list sorting and filtering

Repository lists should be able to sort and filter by:
* Repo size
* Repo permissions
* Repo visibility
* Stars
* Last write timestamp
* Contributor count (yet to be implemented dolthub/ld#4527)
* Commit count (yet to be implemented)

All sort/filter options should be the same across Repo Lists but the initial view will vary by context. For example, the Discover repos might be initially sorted by RepoStar count whereas a user's profile is sorted by LastWriteTimestamp.

The issue defines shared sorting and filtering for repository lists, including size, permissions, visibility, stars, last-write time, contributor count, and commit count. Start by locating the repository-list implementation and determine how each list context selects its initial ordering. Done means all listed options work consistently across repository lists while context-specific defaults remain supported.

Written by the indexing model from the issue text.