Option to only show MSCs that have changed in the last week

Would require tracking changes, with timestamps, and pulling only those that happened in the last week.

Quickly getting into "requiring a db" territory.

Start by reviewing the bot's existing MSC tracking and retrieval flow; no files or tests are identified in the issue. Determine how change timestamps would be stored and how the query should select MSCs changed within the last seven days. Done means the bot can reliably return only recently changed MSCs with persisted change data.

Written by the indexing model from the issue text.